Chapter 2 Notes: Expansion Cards, Storage Devices, and Power Supplies
3.3 Storage Devices: Selecting, Installing, and Configuring
Objective: Given a scenario, select and install storage devices.
Hard drives (HDDs) basics
Speeds (rotational): commonly, faster RPMs generally mean faster data access and transfer rates.
5400\ rpm
7200\ rpm
10000\ rpm
15000\ rpm
Form factors: Refers to the physical size of the drive.
2.5'': Typically used in laptops and compact desktop systems due to smaller size.
3.5'': Standard size for desktop computers and server storage, offering larger capacities.
Interfaces and types: Defines how the drive connects to the motherboard and communicates.
Hard Disk Drives (HDDs): Traditional mechanical drives with spinning platters.
Solid-State Drives (SSDs): Flash-based storage with no moving parts.
NVMe (Non-Volatile Memory Express): A high-performance communication protocol specifically designed for SSDs, leveraging PCIe.
SATA (Serial Advanced Technology Attachment): A common interface for both HDDs and SSDs, offering speeds up to 6 ext{ Gbps}, but slower than PCIe.
PCIe (Peripheral Component Interconnect Express): A high-speed serial expansion bus, used directly by NVMe SSDs for maximum performance.
SSDs use PCIe/NVMe interfaces for higher performance due to direct motherboard communication and lower latency; SATA SSDs are also common but are limited by the SATA interface speed, making them slower than NVMe drives.
Drive configurations (RAID): Redundant Array of Independent Disks, used for data redundancy, performance improvement, or both.
RAID\ 0
RAID\ 1
RAID\ 5
RAID\ 10
Removable storage options: Portable data storage devices.
Flash drives (USB): Portable solid-state storage connecting via USB ports (e.g., USB 2.0, 3.0, 3.1, 3.2, offering varying speeds).
Memory cards: Small, removable flash storage for cameras, phones, and other devices (e.g., SD, microSD, miniSD, CompactFlash, xD Picture Card, Memory Stick).
Optical drives: Use lasers to read and/or write data to optical discs.
CD-ROM (Compact Disc Read-Only Memory)
DVD-ROM (Digital Versatile Disc Read-Only Memory)
BD-ROM (Blu-ray Disc Read-Only Memory)
SSD specifics (brief): advantages and trade-offs
Advantages: Faster start-up and application load times; significantly faster read and write speeds; lower power consumption and heat generation; completely silent operation due to no moving parts; generally more reliable and durable, offering greater resistance to physical shock; higher data density allowing for more storage in smaller form factors.
Disadvantages: More expensive per gigabyte compared to HDDs; finite number of write/erase cycles (longevity is measured in Terabytes Written - TBW, improving over time with wear leveling algorithms and better NAND flash technology) which can theoretically limit the drive's lifespan under heavy write workloads.
Comms interfaces for SSDs
SATA (older/standard): Widely compatible, but performance limited to 6 ext{ Gbps}, which can bottleneck faster SSDs.
PCIe: High-speed, low-latency interface providing direct communication with the CPU, bypassing the slower chipset SATA controller.
NVMe (via PCIe): A logical device interface standard specifically optimized for SSDs to communicate over PCIe, maximizing parallelism, reducing latency, and significantly increasing throughput for high-performance applications.
SSD form factors
mSATA: A miniature SATA interface, often found in older ultra-compact devices like netbooks or embedded systems.
M.2: A versatile compact form factor that supports both SATA and PCIe (NVMe) interfaces. M.2 drives come in various lengths (e.g., $22 imes42 ext{mm}$, $22 imes60 ext{mm}$, $22 imes80 ext{mm}$, $22 imes110 ext{mm}$) and use different keying (B key, M key, B+M key) to indicate interface support (SATA, PCIe x2, PCIe x4).
2.5'' size common for many SSDs: Matches the standard laptop HDD form factor, allowing for easy replacement in existing systems using SATA connections.
RAID, redundancy, and storage strategy
RAID 0: disk striping (data is split across multiple drives); improves performance significantly (read/write speed); offers no redundancy, so if one drive fails, all data is lost; minimum of 2 disks. Typical use: high-performance gaming setups, video editing scratch disks.
RAID 1: disk mirroring (identical copy of data on two or more drives); provides full redundancy, as data is duplicated; capacity equals smallest disk; minimum of 2 disks. Typical use: small servers, critical personal data backup, ensuring data availability.
RAID 5: striping with parity (data and parity information are distributed across multiple drives); offers fault tolerance against a single drive failure; provides a good balance of performance (due to striping) and reliability (due to parity); needs at least 3 disks. Typical use: general-purpose file servers, web servers.
RAID 10: mirroring of a striped set (combines RAID 1 and RAID 0); provides both excellent redundancy and high performance; requires a minimum of 4 disks. Typical use: databases, high-transaction web servers, systems requiring both performance and high data availability.
Removable storage and media (hot-swappable)
Flash memory-based media: Utilizes non-volatile solid-state memory.
USB flash drives: Convenient for quick data transfer and portable storage.
SD, microSD, miniSD, xD, CompactFlash, etc.: Primarily used in cameras, smartphones, and other consumer electronics for expandable storage.
Hot-swappable capability varies by device and interface: Allows insertion and removal of media while the system is running without needing to power down, as long as the operating system properly dismounts the device first (e.g., USB drives).
Optical drives (as storage media options)
CD-ROM: Read-only compact discs, max capacity around 700 ext{ MB}.
DVD-ROM: Read-only digital versatile discs, max capacity around 4.7 ext{ GB} for single layer.
BD-ROM (Blu-ray): Read-only high-definition discs, max capacity up to 25 ext{ GB} for single layer (50 ext{ GB} for dual-layer).
Note: R (recordable) and RW (rewritable) versions are also available for CDs, DVDs, and Blu-rays, allowing for data writing.
3.4 Installing and Configuring Motherboards, CPUs, and Add-On Cards
Expansion cards include: Sound card, Video card (GPU), Capture card, NIC (network interface card), USB expansion card, RAID controller card.
Add-on card considerations
Each card requires its own resources: These traditionally included Interrupt Request (IRQ) lines, Direct Memory Access (DMA) channels, and I/O addresses. While modern Plug and Play (PnP) systems largely automate this, understanding legacy resource allocation can be important for troubleshooting.
Can be configured automatically via Plug and Play (PnP) by the operating system, or manually in the system's BIOS/UEFI settings for older or specialized cards.
Adapter cards often come with unique configuration options and may include proprietary software or utilities for advanced settings and monitoring.
Practical notes
Ensure compatibility with motherboard: Check the slot type (PCIe x1, x4, x8, x16) and generation (e.g., PCIe 3.0, 4.0, 5.0) which dictates the bandwidth available. Higher generation slots offer significantly more bandwidth.
Consider cooling implications for high-power cards (e.g., high-end GPUs, multi-GPU setups) that generate substantial heat and require adequate airflow within the case to prevent thermal throttling and system instability.
Driver software may be required post-installation: Even with Plug and Play, installing the latest vendor-supplied drivers often unlocks full functionality, optimizations, and performance improvements for the card.
Expansion Card Types (Summary)
Video cards (graphics):
Often add-on (discrete GPUs): Dedicated processing units for graphics rendering, offering high performance for gaming, 3D modeling, and video editing. Can be found from brands like NVIDIA (GeForce RTX/GTX) and AMD (Radeon RX).
Can be onboard (integrated graphics): Built into the CPU or motherboard chipset, suitable for basic display output and light multimedia tasks.
Example branding shown: EVGA, GeForce RTX 2070 (illustrative branding for discrete graphics cards).
Multimedia cards:
Sound cards: Enhance audio quality, provide more audio input/output options (e.g., surround sound); can be internal (PCIe) or external (USB).
Video capture cards: Allow recording of video input from external sources (e.g., cameras, game consoles) for streaming or editing.
Network Interface Cards (NIC):
Wired options: Ethernet cards (e.g., Gigabit Ethernet, 10 Gigabit Ethernet, 2.5 Gigabit Ethernet) for connecting to a wired network.
Wireless options: Wi-Fi adapters (e.g., 802.11n, 802.11ac, 802.11ax/Wi-Fi 6) for connecting to wireless networks.
Example: Linksys/WMP54G (802.11g PCI adapter) - an older standard, modern cards use PCIe and support newer Wi-Fi versions.
Input/Output (I/O) cards:
USB expansion cards: Add more USB ports (e.g., USB 3.0, USB 3.1 Type-C) to a system.
eSATA cards: Provide external SATA ports for connecting external drives.
Thunderbolt cards: Offer high-bandwidth connectivity for external devices, supporting data, video, and power delivery over a single cable.
Key implication:
Each expansion card may require its own system resources (IRQ, I/O addresses, DMA channels); installation may vary by card type and manufacturer, often requiring specific drivers and software.
Configuring Expansion Cards
Each card: dedicated resources (IRQ, I/O, DMA as needed)
Plug and Play (PnP) support:
Cards can be auto-configured by the Operating System (OS) to assign resources automatically, greatly simplifying installation.
Some legacy or specialized cards may still require manual configuration of resource settings within the motherboard's BIOS/UEFI.
Adapter cards:
Often include unique configuration options and may require proprietary software or utilities provided by the manufacturer to access advanced features (e.g., GPU overclocking software, sound card equalizers).
Driver and software management
After physical installation, drivers may be auto-installed by the OS from its built-in driver library, or require vendor-supplied software (downloaded from the manufacturer's website or provided on a disc) for optimal performance and compatibility.
General Steps to Install and Configure Expansion Cards
Before installation:
Ensure the computer is powered off and unplugged from the wall outlet to prevent electrical shock and damage to components.
Discharge any static electricity by touching a grounded metal object or wearing an anti-static wrist strap to prevent electrostatic discharge (ESD) damage.
Hardware installation:
Open the computer case.
Locate an available expansion slot (PCIe x1, x4, x8, x16) that matches the card.
Remove the metal slot cover from the back of the case.
Carefully align the card with the slot and press it firmly until it seats correctly. Do not force it.
Secure the card with a screw or retention clip at the back of the case.
Connect any required auxiliary power connectors (e.g., 6-pin or 8-pin PCIe power cables for high-end video cards) from the power supply to the card.
Close the computer case.
After installation:
Boot the computer.
The operating system may automatically detect the new hardware and install appropriate generic drivers via Plug and Play.
If automatic installation fails or for optimal performance, install the appropriate drivers from the card manufacturer's website or installation media.
Troubleshooting:
If the card is not recognized or not functioning correctly, first check the Device Manager in the operating system for hardware conflicts or missing drivers.
Check BIOS/UEFI for configuration settings: Ensure the PCIe slot is enabled, and dedicated graphics options are prioritized if installing a GPU.
Use vendor/manufacturer utility or software for additional configuration and diagnostics. Reinstalling drivers can also resolve issues.
Documentation:
Always consult the card’s documentation for specific installation steps, driver requirements, and troubleshooting tips, as procedures can vary by model and manufacturer.
Hard Disk Drive (HDD) Systems
Core components:
Controller: Electronic circuit on the drive that manages data transfer between the platters and the host system.
Hard disk platters (disks): Magnetic storage surfaces where data is physically stored.
Read/write heads: Small electromagnets that read and write data to the platters.
Host Bus Adapter (HBA): Interface card or integrated motherboard component that connects the drive to the system's external bus (e.g., SATA controller).
Common interface types:
SATA (Serial ATA): The ubiquitous modern interface, using thin, serial cables for data transfer, offering higher speeds and easier cable management than PATA.
PATA (Parallel ATA): An older interface that uses wide ribbon cables and transfers data in parallel, now largely obsolete in new systems due to slower speeds and bulkier cables.
Additional context:
The controller and HBA manage communication between the drive and the motherboard, translating commands and data for proper storage and retrieval.
Anatomy of a Conventional Hard Drive
Key physical elements:
Platters (magnetic storage surfaces): Circular discs coated with a magnetic material where data bits are stored. Multiple platters are often stacked.
Read/write heads: Small electromagnetic transducers that float just above the surface of the platters, reading magnetic patterns and writing new ones. Each platter surface has its own read/write head.
Tracks (circular paths on platters): Concentric circles on the platter surface where data is recorded. Data is written sequentially along these tracks.
Sectors (smallest addressable unit on a track): A wedge-shaped division of a track, typically holding 512 bytes of data, which is the smallest physical unit of storage that the drive can read or write.
Cylinders (collection of tracks at the same radius across platters): A vertical stack of tracks (one on each platter surface) that are at the same radial distance from the center. Data is often written cylinder by cylinder to minimize read/write head movement.
Clusters (allocation units used by file systems): A group of one or more sectors, which is the smallest unit of disk space that an operating system's file system can allocate to a file. Larger clusters can improve performance for large files by reducing fragmentation but may waste space for small files (known as slack space).
Hard Drive Speeds and Sizes
Conventional HDD speeds (rotational): Measured in revolutions per minute (RPM), indicating how fast the platters spin. Higher RPM generally means faster data access times and transfer rates, as read/write heads can access data more quickly.
5400\ rpm
7200\ rpm
10000\ rpm
12000\ rpm
15000\ rpm
Physical sizes/form factors:
3.5'' drives (typical desktop HDDs): Standard size for desktop computers, external desktop drives, and servers, offering high capacities.
2.5'' drives (commonly laptop or compact desktops): Smaller drives, usually found in laptops, gaming consoles, and some external portable drives.
Solid-State Drives (SSDs)
Advantages recap
Faster boot times, significantly faster read/write speeds, lower power consumption, silent operation, more reliable and durable due to no moving parts.
Higher data density per area compared to traditional HDDs.
Disadvantages recap
Higher cost per byte (price per GB) compared to HDDs, though prices are continually decreasing.
Finite number of write/erase cycles (endurance) due to the nature of NAND flash memory. However, this is significantly improving with newer NAND technologies (e.g., TLC, QLC) and advanced wear leveling algorithms (which distribute writes evenly across the NAND cells) and Garbage Collection/TRIM commands (which optimize data management), making them durable enough for typical consumer and enterprise use for many years. Endurance is often measured in Terabytes Written (TBW).
Interfaces and form factors (overview)
SATA SSDs (2.5'' form factor common): Offer a good balance of speed and cost, compatible with most existing systems. Performance is limited by the SATA 6 ext{ Gbps} interface.
PCIe NVMe SSDs for highest performance: Leverage the PCIe bus for direct, high-bandwidth communication with the CPU, offering significantly lower latency and higher throughput compared to SATA SSDs.
NVMe communicates over PCIe buses, offering lower latency and higher throughput by optimizing the command set for flash memory, allowing for much greater parallelism compared to the older AHCI (SATA) protocol.
SSD Communication Interfaces
SATA: Traditional interface for many SSDs; compatible with most existing systems. While faster than HDDs, it can become a bottleneck for high-performance SSDs, limiting actual throughput to around 550 ext{ MB/s}.
PCIe: High-speed serial interface used by NVMe SSDs, providing multiple lanes for data transfer (e.g., PCIe x4, x8), offering theoretical speeds far exceeding SATA (e.g., PCIe 3.0 x4 can reach ~3.94 ext{ GB/s}, PCIe 4.0 x4 can reach ~7.88 ext{ GB/s}).
NVMe: Non-Volatile Memory Express; a highly efficient communication protocol optimized for flash-based storage (SSDs) to maximize parallelism and throughput over the PCIe bus, resulting in significantly reduced latency and greatly increased read/write speeds for modern applications.
SSD Form Factors
Common form factors:
mSATA (miniature SATA): A small form factor designed for compact devices like laptops and embedded systems, connecting via an mSATA slot and using the SATA interface protocol.
M.2: A widely adopted, versatile tiny card/edge connector format used in modern laptops, desktops, and servers. M.2 modules can support either SATA or PCIe/NVMe interfaces, indicated by their keying (B key, M key, or B+M key), and come in various lengths (e.g., 2242, 2260, 2280, 22110) where the first two digits are width (in mm) and the last two are length (in mm).
2.5'' drive form factor: The traditional SSD size, identical to laptop HDDs, which allows for easy replacement of older drives in existing systems. These typically use a SATA interface.
RAID: Redundant Array of Independent (Inexpensive) Disks
Common RAID levels:
RAID\ 0 – disk striping: Data is split into blocks and written across a minimum of 2 disks. This boosts performance (read and write speeds) but provides no data redundancy. If one drive fails, all data in the array is lost. Best for non-critical data requiring high speed.
RAID\ 1 – disk mirroring: Data is identically written to two or more disks simultaneously. This provides excellent data redundancy; if one drive fails, the data is still accessible from the other disk(s). Capacity is limited to that of a single drive (or the smallest drive in the array). Requires a minimum of 2 disks. Ideal for critical data where reliability is paramount.
RAID\ 5 – striping with parity: Data blocks and a parity block (for error correction and recovery) are distributed across a minimum of 3 disks. This offers fault tolerance (can withstand one drive failure) and improved read performance due to striping, with a good balance of capacity and redundancy. Common in servers.
RAID\ 10 – mirroring of a striped set: Combines the striping of RAID 0 with the mirroring of RAID 1. Data is striped across pairs of mirrored disks. This configuration offers both high performance and robust redundancy, capable of surviving the failure of one disk in each mirrored set. Requires a minimum of 4 disks (2 mirrored pairs). Excellent for applications demanding both high I/O performance and high data availability.
Removable Storage and Media
Flash memory-based storage: Utilizes non-volatile flash memory chips to store data, providing durability and portability without moving parts.
USB flash drives: Highly portable devices that connect via a USB port, commonly used for quick file transfers, backups, and storing portable applications.
SD and other memory cards (e.g., SD, microSD, miniSD, high-capacity variants like SDHC, SDXC): Used extensively in digital cameras, smartphones, drones, and other portable electronic devices for expanding storage capacity.
Hot-swappable capabilities: The ability to insert or remove media (like USB drives or SD cards) while the system is running, without needing to power down. This depends on the device's interface and the operating system's support for safe removal (ejecting the device before physical removal).
Optical Drives
Types of optical media support:
CD-ROM: Read-only, low-capacity optical discs (approx. 700 ext{ MB}), primarily used for software distribution and audio.
DVD-ROM: Read-only, higher-capacity optical discs (approx. 4.7 ext{ GB} single layer, 8.5 ext{ GB} dual layer), widely used for movies, software, and data archives.
BD-ROM (Blu-ray): Read-only, high-definition optical discs (approx. 25 ext{ GB} single layer, 50 ext{ GB} dual layer), primarily used for high-definition video content and large data backups.
Some drives also support R (recordable) and RW (rewritable) formats for these media types.
Power Supplies (Extended)
Power supply input considerations:
Voltage input options: Most modern power supplies are auto-switching, adapting automatically to the input voltage. However, some older or specialized units may have a manual switch to select between 115 ext{V} (for North America) or 220 ext{V} (for Europe and other regions). Incorrect selection can damage the PSU or components.
Power supply outputs and ratings:
Multiple rails with various voltages: Convert AC input into DC voltages required by computer components.
3.3 ext{V} and 5.5 ext{V}: Primarily used for motherboard logic, RAM, and some drive components.
12 ext{V}: The most critical rail, powering the CPU, GPU, and drive motors. High-power components draw heavily from this rail.
Wattage rating: Indicates the maximum total power the PSU can deliver. It must be sufficient (with ample headroom) to power all system components, especially the CPU, GPU, and multiple drives, under peak load.
Connectors and form factors:
ATX: The dominant standard for desktop power supplies.
ATX12V: A common standard for desktop/workstation PSUs, supplying power to the motherboard (20/24-pin), CPU (4/8-pin EPS12V), and PCIe cards (6/8-pin).
EPS12V: Primarily for server motherboards or high-end workstations, providing robust power delivery for multi-processor setups.
SATA power connectors: Provide 3.3 ext{V}, 5 ext{V}, and 12 ext{V} to SATA drives.
Molex (4-pin): Older connector for IDE drives and case fans.
PCIe (6-pin/8-pin): Dedicated power connectors for high-power graphics cards and other expansion cards.
Modular vs. non-modular:
Modular: Cables can be detached from the PSU unit. This reduces cable clutter inside the case, improves airflow, and simplifies cable management, as you only connect the cables you need.
Non-modular: All cables are permanently attached to the PSU, often leading to excess unused cables within the case, potentially affecting airflow and aesthetics.
Semi-modular: A hybrid where essential cables (e.g., 24-pin ATX, 8-pin EPS/CPU) are fixed, while others are detachable.
Redundancy and headroom:
Redundant power supply: Multiple independent power supply units within a system (often found in servers) that can take over immediately if one unit fails, ensuring uninterrupted operation for mission-critical systems and higher availability.
Ensure wattage rating exceeds peak load: Always select a power supply with a wattage rating significantly higher than the calculated peak power consumption of all components (e.g., 20-30% headroom) to ensure stability, efficiency, and longevity, especially during bursts of high activity from the CPU and GPU.
Modular and Redundant Power Supplies (Notes)
Modular power supplies:
Allow selective cabling (CPU/PCIe power, motherboard power, drive power) to keep the case tidy and improve internal airflow by eliminating unnecessary cables. This also makes installation and upgrades cleaner.
Redundant power supplies:
Typically found in enterprise-grade servers and critical network equipment. They provide uninterrupted power in case one unit fails, as a secondary (or tertiary) unit immediately takes over, preventing downtime. Some redundant PSUs are hot-swappable for seamless replacement.
Common cabling categories shown in practice:
CPU/PCIe cables: Dedicated power lines for the central processing unit and high-power graphics cards or other PCIe expansion cards.
Peripheral, IDE, SATA/Molex connectors: Provide power to storage drives (HDDs, SSDs, optical drives) and other accessories like case fans or legacy peripherals.
Uninterruptible Power Supplies (UPS)
Purpose: Provide temporary battery backup power during power outages or fluctuations, and offer surge protection against electrical spikes, safeguarding sensitive equipment from damage and data loss.
Typical features:
Battery backup: Provides power for a limited time (minutes to hours) during an outage, allowing for graceful shutdown of systems or continuous operation through brief interruptions.
Surge protection: Absorbs voltage spikes and surges, protecting connected electronics from damage.
Data port for management and signaling: Allows the UPS to communicate with the computer (e.g., via USB or serial cable) to monitor power status, trigger automatic shutdowns when the battery is low, and manage power settings.
Brands/examples in study materials (illustrative): APC Back-UPS, CyberPower, Eaton.
Practical use: Protects desktop computers, servers, network equipment, and other valuable electronics from power disturbances. It allows users to save work and shut down systems properly during an outage, preventing data corruption and hardware damage.
Quick Reference: Key Terms and Concepts
NVMe: Non-Volatile Memory Express; a high-performance communication protocol specifically designed for SSDs, leveraging the PCIe bus for maximum speed and lowest latency.
SATA: Serial ATA; a common interface for HDDs and SSDs, connecting them to the motherboard for data transfer.
PCIe: Peripheral Component Interconnect Express; a high-speed serial expansion bus used for connecting expansion cards (like GPUs, NICs, and NVMe SSDs) directly to the CPU or chipset.
M.2: A compact motherboard slot and form factor for SSDs and other expansion cards, supporting both SATA and PCIe (NVMe) interfaces and coming in various lengths.
mSATA: Miniature SATA; a smaller form factor for SSDs, primarily found in older compact devices, using the SATA interface protocol.
RAID: Redundant Array of Independent Disks; a technology that combines multiple physical disk drives into a single logical unit for data redundancy, performance improvement, or both.
HBA: Host Bus Adapter; a circuit or card that provides an interface between a computer's host system and a storage device (e.g., a SATA controller).
PATA: Parallel ATA; an older, slower HDD interface that uses wide ribbon cables, largely superseded by SATA.
Boot/driver flow: The typical sequence for installing a new hardware component: physically install the card, boot the computer, install the appropriate drivers (either automatically via PnP or manually from vendor software), and use BIOS/UEFI settings for advanced configuration or troubleshooting as needed. Always consult documentation.
Hot-swappable: The ability to safely connect or disconnect a device (e.g., a USB drive, a redundant power supply unit) to/from a running system without needing to power down or reboot.
Equations and Numeric References (LaTeX)
Drive speeds: \text{Speed} = \text{rpm} where rpm \in {5400, 7200, 10000, 12000, 15000} revolutions per minute for HDDs.
Power rails (example): \mathbf{V{\text{out}}} = {V{3.3} = 3.3\,\text{V}, V{5} = 5\,\text{V}, V{12} = 12\,\text{V}} commonly supplied by ATX power supplies.
Input voltages: \mathbf{V_{\text{in}}} = {115\,\text{V}, 220\,\text{V}}
RAID levels (conceptual):
\text{RAID}_0: \text{striping (performance)}
\text{RAID}_1: \text{mirroring (redundancy)}
\text{RAID}_5: \text{striping with parity (fault tolerance)}
\text{RAID}_\text{10}: \text{mirrored striped sets (performance and redundancy)}
Connections to Real-World Relevance
Choosing the right storage depends heavily on performance needs (e.g., NVMe for high-speed applications), capacity requirements, and fault tolerance (decided by RAID levels for data protection).
NVMe over PCIe provides the best performance for modern workloads like gaming, content creation, and highly demanding applications, while SATA SSDs offer a cost-effective balance of speed for general computing.
Proper power budgeting (ensuring adequate wattage and considering redundancy with redundant PSUs and UPS) is essential for system reliability, particularly in servers, workstations with multiple GPUs, or systems with numerous drives, to prevent unexpected shutdowns and component damage.
Understanding form factors (2.5'' vs 3.5'' for HDDs, M.2, mSATA for SSDs) is crucial for ensuring compatibility when buying or upgrading components for various devices like laptops, desktops, and embedded systems.
Upgrading or configuring expansion cards requires careful attention to resource allocation (IRQ/DMA considerations, especially with legacy hardware), proper BIOS/UEFI settings, and installing correct drivers to ensure devices function correctly and the system remains stable.
Foundational Principles Touched
Plug and Play (PnP) greatly simplifies hardware installation by automating resource allocation, but understanding underlying resource management concepts (IRQs, DMAs) can be vital for troubleshooting older or specialized hardware.
The distinction between HDDs and SSDs represents a fundamental shift in storage technology: mechanical (platters, heads) vs. solid-state (flash memory), with distinct trade-offs in terms of speed, durability, power consumption, noise, and endurance (write cycles).
System reliability is significantly enhanced by implementing redundancy measures (such as RAID configurations for data, redundant power supplies for hardware, and Uninterruptible Power Supplies - UPS - for power interruptions) and the ability to gracefully handle power outages to prevent data loss and hardware damage.
3.3 Storage Devices: Selecting, Installing, and Configuring
Objective: Given a scenario, select and install storage devices.
Hard drives (HDDs) basics
Speeds (rotational): commonly, faster RPMs generally mean faster data access and transfer rates by reducing the time it takes for data to pass under the read/write heads.
5400\ rpm
7200\ rpm
10000\ rpm
15000\ rpm
Form factors: Refers to the physical size of the drive.
2.5'': Typically used in laptops, compact desktop systems, and external portable drives due to their smaller size and reduced power consumption.
3.5'': Standard size for desktop computers, servers, and network attached storage (NAS) devices, offering larger capacities and often better performance than their 2.5'' counterparts in HDDs.
Interfaces and types: Defines how the drive connects to the motherboard and communicates.
Hard Disk Drives (HDDs): Traditional mechanical drives with spinning platters and read/write heads.
Solid-State Drives (SSDs): Flash-based storage with no moving parts, offering superior speed and durability.
NVMe (Non-Volatile Memory Express): A high-performance communication protocol specifically designed for SSDs, leveraging the PCIe bus for direct, low-latency communication with the CPU.
SATA (Serial Advanced Technology Attachment): A common interface for both HDDs and SSDs, offering speeds up to 6\ \text{Gbps}. While widely compatible, it can become a bottleneck for high-speed SSDs compared to PCIe.
PCIe (Peripheral Component Interconnect Express): A high-speed serial expansion bus, used directly by NVMe SSDs for maximum performance by providing dedicated, high-bandwidth lanes for data transfer.
SSDs use PCIe/NVMe interfaces for higher performance due to direct motherboard communication and lower latency; SATA SSDs are also common but are limited by the SATA interface speed, making them slower than NVMe drives.
Drive configurations (RAID): Redundant Array of Independent Disks, used for data redundancy, performance improvement, or both.
RAID\ 0
RAID\ 1
RAID\ 5
RAID\ 10
Removable storage options: Portable data storage devices.
Flash drives (USB): Portable solid-state storage connecting via USB ports. Different USB versions (e.g., USB 2.0, 3.0, 3.1, 3.2, 4.0) offer varying speeds, with newer versions providing significantly faster data transfer rates.
Memory cards: Small, removable flash storage for cameras, phones, and other devices (e.g., SD, microSD, miniSD, CompactFlash, xD Picture Card, Memory Stick).
Optical drives: Use lasers to read and/or write data to optical discs.
CD-ROM (Compact Disc Read-Only Memory)
DVD-ROM (Digital Versatile Disc Read-Only Memory)
BD-ROM (Blu-ray Disc Read-Only Memory)
SSD specifics (brief): advantages and trade-offs
Advantages: Faster start-up and application load times; significantly faster read and write speeds; lower power consumption and heat generation; completely silent operation due to no moving parts; generally more reliable and durable, offering greater resistance to physical shock; higher data density allowing for more storage in smaller form factors.
Disadvantages: More expensive per gigabyte compared to HDDs; finite number of write/erase cycles (longevity is measured in Terabytes Written - TBW, improving over time with advanced wear leveling algorithms and better NAND flash technology like TLC and QLC) which can theoretically limit the drive's lifespan under heavy write workloads.
Comms interfaces for SSDs
SATA (older/standard): Widely compatible, but performance limited to 6\ \text{Gbps} (around 550\ \text{MB/s} actual throughput), which can bottleneck faster SSDs.
PCIe: High-speed, low-latency interface providing direct communication with the CPU, bypassing the slower chipset SATA controller. Theoretical speeds vary by generation and lane count (e.g., PCIe 3.0 x4 can reach ~3.94\ \text{GB/s}, PCIe 4.0 x4 can reach ~7.88\ \text{GB/s}).
NVMe (via PCIe): A logical device interface standard specifically optimized for SSDs to communicate over PCIe, maximizing parallelism, reducing latency, and significantly increasing throughput for high-performance applications like intensive gaming, 4K video editing, and large database operations.
SSD form factors
mSATA: A miniature SATA interface, often found in older ultra-compact devices like netbooks or embedded systems.
M.2: A versatile compact form factor that supports both SATA and PCIe (NVMe) interfaces. M.2 drives come in various lengths (e.g., $22\times42\ \text{mm}$, $22\times60\ \text{mm}$, $22\times80\ \text{mm}$, $22\times110\ \text{mm}$) and use different keying (B key for SATA/PCIe x2, M key for PCIe x4, B+M key for both) to indicate interface support.
2.5'' size common for many SSDs: Matches the standard laptop HDD form factor, allowing for easy replacement in existing systems using SATA connections.
RAID, redundancy, and storage strategy
RAID 0: disk striping (data is split across multiple drives); improves performance significantly (read/write speed); offers no redundancy, so if one drive fails, all data is lost; minimum of 2 disks. Typical use: high-performance gaming setups, video editing scratch disks, and other applications where speed is paramount and data loss is acceptable.
RAID 1: disk mirroring (identical copy of data on two or more drives); provides full redundancy, as data is duplicated; capacity equals smallest disk; minimum of 2 disks. Typical use: small servers, critical personal data backup, ensuring data availability for mirrored critical files.
RAID 5: striping with parity (data and parity information are distributed across multiple drives); offers fault tolerance against a single drive failure; provides a good balance of performance (due to striping) and reliability (due to parity); needs at least 3 disks. Typical use: general-purpose file servers, web servers, and applications requiring both good performance and data protection.
RAID 10: mirroring of a striped set (combines RAID 1 and RAID 0); provides both excellent redundancy and high performance; requires a minimum of 4 disks. Typical use: databases, high-transaction web servers, and systems requiring both extreme performance and high data availability, such as virtualized environments.
Removable storage and media (hot-swappable)
Flash memory-based media: Utilizes non-volatile solid-state memory.
USB flash drives: Convenient for quick data transfer and portable storage. Speeds vary significantly based on USB standard (e.g., USB 3.0 is considerably faster than USB 2.0).
SD, microSD, miniSD, xD, CompactFlash, etc.: Primarily used in cameras, smartphones, drones, and other consumer electronics for expandable storage.
Hot-swappable capability varies by device and interface: Allows insertion and removal of media while the system is running without needing to power down, as long as the operating system properly dismounts (ejects) the device first to prevent data corruption (e.g., USB drives).
Optical drives (as storage media options)
CD-ROM: Read-only compact discs, max capacity around 700\ \text{MB}. Evolved from audio CDs, used primarily for software distribution and multimedia.
DVD-ROM: Read-only digital versatile discs, max capacity around 4.7\ \text{GB} for single layer (8.5\ \text{GB} for dual layer), widely used for movies, larger software applications, and data archives.
BD-ROM (Blu-ray): Read-only high-definition discs, max capacity up to 25\ \text{GB} for single layer (50\ \text{GB} for dual-layer), primarily used for high-definition video content (e.g., movies in 1080p, 4K) and very large data backups.
Note: R (recordable) and RW (rewritable) versions are also available for CDs, DVDs, and Blu-rays, allowing for data writing to once or multiple times, respectively.
3.4 Installing and Configuring Motherboards, CPUs, and Add-On Cards
Expansion cards include: Sound card, Video card (GPU), Capture card, NIC (network interface card), USB expansion card, RAID controller card.
Add-on card considerations
Each card requires its own resources: These traditionally included Interrupt Request (IRQ) lines (used for hardware to signal the CPU), Direct Memory Access (DMA) channels (allowing hardware to access memory directly without CPU intervention), and I/O addresses (unique addresses for peripherals to communicate with the CPU). While modern Plug and Play (PnP) systems largely automate this, understanding legacy resource allocation can be important for troubleshooting older or specialized cards.
Can be configured automatically via Plug and Play (PnP) by the operating system, or manually in the system's BIOS/UEFI settings for older or specialized cards that may not be fully PnP compatible.
Adapter cards often come with unique configuration options and may include proprietary software or utilities for advanced settings and monitoring (e.g., overclocking software for GPUs, virtual mixer software for sound cards).
Practical notes
Ensure compatibility with motherboard: Check the slot type (PCIe x1, x4, x8, x16) and generation (e.g., PCIe 3.0, 4.0, 5.0) which dictates the bandwidth available. Higher generation slots offer significantly more bandwidth, crucial for high-performance components.
Consider cooling implications for high-power cards (e.g., high-end GPUs, multi-GPU setups) that generate substantial heat and require adequate airflow within the case to prevent thermal throttling and system instability. Larger cases and additional case fans may be necessary.
Driver software may be required post-installation: Even with Plug and Play, installing the latest vendor-supplied drivers often unlocks full functionality, optimizations, and performance improvements for the card, and resolves compatibility issues.
Expansion Card Types (Summary)
Video cards (graphics):
Often add-on (discrete GPUs): Dedicated processing units for graphics rendering, offering high performance for gaming, 3D modeling, and video editing. Can be found from brands like NVIDIA (GeForce RTX/GTX) and AMD (Radeon RX). These cards have their own dedicated VRAM (Video RAM).
Can be onboard (integrated graphics): Built into the CPU (e.g., Intel HD/Iris Xe, AMD Radeon Graphics) or motherboard chipset, suitable for basic display output, web browsing, and light multimedia tasks, sharing system RAM.
Example branding shown: EVGA, GeForce RTX 2070 (illustrative branding for discrete graphics cards).
Multimedia cards:
Sound cards: Enhance audio quality, provide more audio input/output options (e.g., surround sound, digital output, specialized inputs for microphones or instruments); can be internal (PCIe) or external (USB).
Video capture cards: Allow recording of video input from external sources (e.g., cameras, game consoles, other computers) for streaming, editing, or archiving purposes.
Network Interface Cards (NIC):
Wired options: Ethernet cards (e.g., Gigabit Ethernet, 10 Gigabit Ethernet, 2.5 Gigabit Ethernet) for connecting to a wired network, offering stable and high-speed local area network (LAN) connections.
Wireless options: Wi-Fi adapters (e.g., 802.11n, 802.11ac, 802.11ax/Wi-Fi 6, Wi-Fi 6E) for connecting to wireless networks, providing flexibility and mobility. Many newer models also include Bluetooth.
Example: Linksys/WMP54G (802.11g PCI adapter) - an older standard, modern cards primarily use PCIe and support newer, faster Wi-Fi versions (e.g., Wi-Fi 6/6E).
Input/Output (I/O) cards:
USB expansion cards: Add more USB ports (e.g., USB 3.0, USB 3.1 Type-C, USB 3.2, USB 4) to a system, useful when native ports are insufficient or older standards.
eSATA cards: Provide external SATA ports for connecting external drives, offering performance comparable to internal SATA drives.
Thunderbolt cards: Offer high-bandwidth connectivity for external devices, supporting data, video, and power delivery over a single cable, typically utilizing a USB-C connector.
Key implication:
Each expansion card may require its own system resources (IRQ, I/O addresses, DMA channels); installation may vary by card type and manufacturer, often requiring specific drivers and software for full functionality.
Configuring Expansion Cards
Each card: dedicated resources (IRQ, I/O, DMA as needed)
Plug and Play (PnP) support:
Cards can be auto-configured by the Operating System (OS) to assign resources automatically, greatly simplifying installation and eliminating manual configuration of jumpers or switches.
Some legacy or specialized cards may still require manual configuration of resource settings within the motherboard's BIOS/UEFI settings, especially if the OS fails to allocate resources correctly or if conflicts arise.
Adapter cards:
Often include unique configuration options and may require proprietary software or utilities provided by the manufacturer to access advanced features (e.g., GPU overclocking software, sound card equalizers, network QoS settings).
Driver and software management
After physical installation, drivers may be auto-installed by the OS from its built-in driver library, or require vendor-supplied software (downloaded from the manufacturer's website or provided on a disc) for optimal performance, compatibility, and access to all features.
General Steps to Install and Configure Expansion Cards
Before installation:
Ensure the computer is powered off and unplugged from the wall outlet to prevent electrical shock and damage to components.
Discharge any static electricity by touching a grounded metal object (like the metal chassis of the computer case) or wearing an anti-static wrist strap to prevent electrostatic discharge (ESD) damage to sensitive electronic components.
Hardware installation:
Open the computer case.
Locate an available expansion slot (PCIe x1, x4, x8, x16) that matches the card. Ensure it's the correct generation and physical size for the card.
Remove the metal slot cover from the back of the case.
Carefully align the card with the slot and press it firmly and evenly until it seats correctly. Do not force it.
Secure the card with a screw or retention clip at the back of the case to prevent it from coming loose.
Connect any required auxiliary power connectors (e.g., 6-pin or 8-pin PCIe power cables for high-end video cards, or Molex connectors for some older cards) from the power supply to the card.
Close the computer case, ensuring all panels are secure and screws are tightened.
After installation:
Boot the computer.
The operating system may automatically detect the new hardware and install appropriate generic drivers via Plug and Play.
If automatic installation fails or for optimal performance, install the appropriate drivers from the card manufacturer's website or installation media. Always prioritize vendor-supplied drivers for full functionality.
Troubleshooting:
If the card is not recognized or not functioning correctly, first check the Device Manager in the operating system for hardware conflicts, missing drivers, or error codes.
Check BIOS/UEFI for configuration settings: Ensure the PCIe slot is enabled, and dedicated graphics options are prioritized if installing a GPU. Disable integrated graphics if necessary.
Use vendor/manufacturer utility or software for additional configuration and diagnostics. Reinstalling drivers (especially clean installations after using a driver uninstaller) can also resolve issues.
Verify sufficient power supply wattage and proper power connections to the card.
Documentation:
Always consult the card’s documentation for specific installation steps, driver requirements, and troubleshooting tips, as procedures can vary by model and manufacturer. The motherboard manual can also provide valuable information regarding slot configurations.
Hard Disk Drive (HDD) Systems
Core components:
Controller: Electronic circuit on the drive that manages data transfer between the platters and the host system, handling tasks like error correction and data buffering.
Hard disk platters (disks): Circular, rigid magnetic storage surfaces where data is physically stored in magnetic bits. Multiple platters are often stacked on a spindle.
Read/write heads: Small electromagnets that float just above the surface of the platters (without touching), reading magnetic patterns and writing new ones. Each platter surface typically has its own pair of read/write heads.
Host Bus Adapter (HBA): Interface card or integrated motherboard component (e.g., a SATA controller) that connects the drive to the system's external bus, translating commands between the CPU and the drive controller.
Common interface types:
SATA (Serial ATA): The ubiquitous modern interface, using thin, serial cables for data transfer, offering higher speeds and easier cable management than PATA. It supports hot-swapping.
PATA (Parallel ATA): An older interface that uses wide ribbon cables and transfers data in parallel, now largely obsolete in new systems due to slower speeds, bulkier cables, and limited device per channel (master/slave configuration).
Additional context:
The controller and HBA manage communication between the drive and the motherboard, translating commands and data for proper storage and retrieval, ensuring data integrity and efficient operation.
Anatomy of a Conventional Hard Drive
Key physical elements:
Platters (magnetic storage surfaces): Circular discs coated with a ferromagnetic material where data bits are stored magnetically. Multiple platters are often stacked on a central spindle and spin at high RPMs.
Read/write heads: Small electromagnetic transducers mounted on an actuator arm that float just micrometers above the surface of the platters, reading magnetic patterns and writing new ones as the platters spin. Each platter surface has its own pair of heads (one for top, one for bottom).
Tracks (circular paths on platters): Concentric circles on the platter surface where data is recorded. Data is written sequentially along these tracks, similar to grooves on a vinyl record but discrete.
Sectors (smallest addressable unit on a track): A wedge-shaped division of a track, typically holding 512 bytes of user data (plus error correction codes and other overhead), which is the smallest physical unit of storage that the drive can read or write. Newer drives use 4KB (4096 byte) sectors known as Advanced Format.
Cylinders (collection of tracks at the same radius across platters): A vertical stack of tracks (one on each platter surface) that are at the same radial distance from the center. Data is often written cylinder by cylinder to minimize read/write head movement (seek time) and improve sequential access performance.
Clusters (allocation units used by file systems): A group of one or more sectors, which is the smallest unit of disk space that an operating system's file system (like NTFS or FAT32) can allocate to a file. Larger clusters can improve performance for large files by reducing fragmentation but may waste space for small files (known as slack space).
Hard Drive Speeds and Sizes
Conventional HDD speeds (rotational): Measured in revolutions per minute (RPM), indicating how fast the platters spin. Higher RPM generally means faster data access times (reduced rotational latency) and higher sustained transfer rates, as read/write heads can access data more quickly and read more data per second.
5400\ rpm
7200\ rpm
10000\ rpm
12000\ rpm
15000\ rpm
Physical sizes/form factors:
3.5'' drives (typical desktop HDDs): Standard size for desktop computers, external desktop drives, and servers, offering high capacities from 1TB to 20TB+.
2.5'' drives (commonly laptop or compact desktops): Smaller drives, usually found in laptops, gaming consoles, and some external portable drives. Capacities typically range up to 5TB for HDDs.
Solid-State Drives (SSDs)
Advantages recap
Faster boot times, significantly faster read/write speeds, lower power consumption, silent operation, more reliable and durable due to no moving parts.
Higher data density per area compared to traditional HDDs, allowing for more storage in smaller devices.
Disadvantages recap
Higher cost per byte (price per GB) compared to HDDs, though prices are continually decreasing as technology advances and production scales.
Finite number of write/erase cycles (endurance) due to the nature of NAND flash memory cells degrading with each program/erase cycle. However, this is significantly improving with newer NAND technologies (e.g., TLC, QLC) and advanced wear leveling algorithms (which distribute writes evenly across the NAND cells to prolong life) and Garbage Collection/TRIM commands (which optimize data management), making them durable enough for typical consumer and enterprise use for many years. Endurance is often measured in Terabytes Written (TBW).
Interfaces and form factors (overview)
SATA SSDs (2.5'' form factor common): Offer a good balance of speed and cost, compatible with most existing systems with SATA ports. Performance is limited by the SATA 6\ \text{Gbps} interface (approx. 550\ \text{MB/s}).
PCIe NVMe SSDs for highest performance: Leverage the PCIe bus for direct, high-bandwidth communication with the CPU, offering significantly lower latency and higher sequential and random throughput compared to SATA SSDs.
NVMe communicates over PCIe buses, offering lower latency and higher throughput by optimizing the command set for flash memory, allowing for much greater parallelism compared to the older AHCI (SATA) protocol. This enables thousands of simultaneous commands versus tens for SATA.
SSD Communication Interfaces
SATA: Traditional interface for many SSDs; compatible with most existing systems. While faster than HDDs, it can become a bottleneck for high-performance SSDs, limiting actual throughput to around 550\ \text{MB/s} because the 6\ \text{Gbps} (Gigabits per second) theoretical speed translates to lower real-world bandwidth after overhead.
PCIe: High-speed serial interface used by NVMe SSDs, providing multiple lanes for data transfer (e.g., PCIe x4, x8). Each lane offers significant bandwidth (e.g., PCIe 3.0 offers about 985\ \text{MB/s} per lane; PCIe 4.0 doubles this to about 1.97\ \text{GB/s} per lane). Thus, PCIe 3.0 x4 can reach ~3.94\ \text{GB/s}, PCIe 4.0 x4 can reach ~7.88\ \text{GB/s} theoretical max speeds.
NVMe: Non-Volatile Memory Express; a highly efficient communication protocol optimized for flash-based storage (SSDs) to maximize parallelism and throughput over the PCIe bus, resulting in significantly reduced latency and greatly increased read/write speeds for modern applications. It allows SSDs to take full advantage of their inherent speed capabilities.
SSD Form Factors
Common form factors:
mSATA (miniature SATA): A small form factor designed for compact devices like ultra-thin laptops and embedded systems, connecting via an mSATA slot and using the SATA interface protocol. It's largely superseded by M.2.
M.2: A widely adopted, versatile tiny card/edge connector format used in modern laptops, desktops, and servers. M.2 modules can support either SATA or PCIe/NVMe interfaces, indicated by their keying (B key typically for SATA or PCIe x2, M key typically for PCIe x4, or B+M key for compatibility with both SATA and PCIe x2 slots), and come in various lengths (e.g., 2242, 2260, 2280, 22110 where the first two digits are width (in mm) and the last two are length (in mm)). $2280$ is the most common size.
2.5'' drive form factor: The traditional SSD size, identical to laptop HDDs, which allows for easy replacement of older drives in existing systems. These typically use a SATA interface and are often chosen for compatibility and ease of installation in standard drive bays.
RAID: Redundant Array of Independent (Inexpensive) Disks
Common RAID levels:
RAID\ 0 – disk striping: Data is split into blocks and written across a minimum of 2 disks. This boosts performance (read and write speeds) by allowing simultaneous access to multiple drives but provides no data redundancy. If one drive fails, all data in the array is lost. Best for non-critical data requiring high speed, like video editing scratch disks or gaming libraries.
RAID\ 1 – disk mirroring: Data is identically written to two or more disks simultaneously. This provides excellent data redundancy; if one drive fails, the data is still accessible from the redundant disk(s). Capacity is limited to that of a single drive (or the smallest drive in the array). Requires a minimum of 2 disks. Ideal for critical data where reliability is paramount, such as operating system drives or small business servers.
RAID\ 5 – striping with parity: Data blocks and a parity block (for error correction and recovery) are distributed across a minimum of 3 disks. This offers fault tolerance against a single drive failure (the lost data can be reconstructed from the remaining data and parity) and improved read performance due to striping, with a good balance of capacity and redundancy. Common in general-purpose file servers and web servers.
RAID\ 10 – mirroring of a striped set: Combines the striping of RAID 0 with the mirroring of RAID 1. Data is striped across pairs of mirrored disks. This configuration offers both high performance and robust redundancy (can survive the failure of one disk in each mirrored set, or multiple if they are in different mirrored sets). Requires a minimum of 4 disks (2 mirrored pairs). Excellent for applications demanding both high I/O performance and high data availability, such as databases and high-transaction web servers.
Removable Storage and Media
Flash memory-based storage: Utilizes non-volatile flash memory chips to store data, providing durability, shock resistance, and portability without moving parts.
USB flash drives: Highly portable devices that connect via a USB port, commonly used for quick file transfers, backups, and storing portable applications. Varieties include USB 2.0, USB 3.0/3.1 Gen 1 (SuperSpeed), USB 3.1 Gen 2 (SuperSpeed+), USB 3.2, and USB 4, each offering increasing speeds.
SD and other memory cards (e.g., SD, microSD, miniSD, high-capacity variants like SDHC, SDXC, and ultra-high-speed standards like UHS-I, UHS-II): Used extensively in digital cameras, smartphones, drones, and other portable electronic devices for expanding storage capacity and transferring media.
Hot-swappable capabilities: The ability to insert or remove media (like USB drives or SD cards, or even some redundant hard drives and power supplies) while the system is running, without needing to power down. This depends on the device's interface (e.g., native USB support) and the operating system's support for safe removal (ejecting the device before physical removal is crucial to prevent data corruption).
Optical Drives
Types of optical media support:
CD-ROM: Read-only, low-capacity optical discs (approx. 700\ \text{MB}). Primarily used for software distribution, audio CDs, and small data archives. Data is typically written at speeds like 52x (where 1x is 150\ \text{KB/s}).
DVD-ROM: Read-only, higher-capacity optical discs (approx. 4.7\ \text{GB} single layer, 8.5\ \text{GB} dual layer). Widely used for movies, larger software applications, and data archives. Speeds measured in x multiples of 1.32\ \text{MB/s}.
BD-ROM (Blu-ray): Read-only, high-definition optical discs (approx. 25\ \text{GB} single layer, 50\ \text{GB} dual layer, and higher for triple/quad layer discs up to 128\ \text{GB}). Primarily used for high-definition video content (e.g., movies in 1080p, 4K) and very large data backups. Speeds measured in x multiples of 4.5\ \text{MB/s}.
Some drives also support R (recordable, e.g., CD-R, DVD-R, BD-R) and RW (rewritable, e.g., CD-RW, DVD-RW, BD-RE) formats for these media types, allowing for data writing once or multiple times, respectively. Optical drives are less common in modern PCs due to the prevalence of digital distribution and high-capacity flash storage.
Power Supplies (Extended)
Power supply input considerations:
Voltage input options: Most modern power supplies are auto-switching, adapting automatically to the input voltage range (e.g., 100\ \text{V} - 240\ \text{V}). However, some older or specialized units may have a manual switch to select between 115\ \text{V} (for North America) or 220\ \text{V} (for Europe and other regions). Incorrect selection can damage the PSU or connected components if switched to the wrong voltage.
Power supply outputs and ratings:
Multiple rails with various voltages: Convert AC input from the wall into stable DC voltages required by computer components.
3.3\ \text{V} and 5.5\ \text{V}: Primarily used for motherboard logic, RAM, and some drive components (e.g., SSD controllers, older IDE drives).
12\ \text{V}: The most critical rail, powering the CPU, GPU, and drive motors. Modern high-power components draw heavily from this rail, so its stability and capacity are paramount for system performance and reliability.
Wattage rating: Indicates the maximum total power the PSU can deliver across all its rails. It must be sufficient (with ample headroom) to power all system components, especially the CPU, GPU, and multiple drives, under peak load. Overestimating needed wattage slightly is generally safer than underestimating.
Connectors and form factors:
ATX: The dominant standard for desktop power supplies, defining the physical dimensions and mounting points. Full-size ATX PSUs are the most common.
ATX12V: A common standard for desktop/workstation PSUs, supplying power to the motherboard (20/24-pin main connector), CPU (4/8-pin EPS12V), and PCIe cards (6/8-pin). Variations include microATX and SFX for smaller cases.
EPS12V: Primarily for server motherboards or high-end workstations, providing robust power delivery for multi-processor setups, often with dual 8-pin CPU connectors.
SATA power connectors: Provide 3.3\ \text{V}, 5\ \text{V}, and 12\ \text{V} to SATA drives (HDDs, SSDs, optical drives).
Molex (4-pin): Older connector for IDE drives, case fans, and some legacy peripherals. Still found on PSUs for backward compatibility or niche uses.
PCIe (6-pin/8-pin): Dedicated power connectors for high-power graphics cards and other PCIe expansion cards, ensuring stable power delivery directly to the expansion card.
Modular vs. non-modular:
Modular: Cables can be detached from the PSU unit. This reduces cable clutter inside the case, improves airflow, and simplifies cable management, as you only connect the cables you need. Offers a cleaner build and easier upgrades.
Non-modular: All cables are permanently attached to the PSU, often leading to excess unused cables within the case, potentially affecting airflow and aesthetics due to bundling unused cables.
Semi-modular: A hybrid where essential cables (e.g., 24-pin ATX, 8-pin EPS/CPU) are fixed, while others (like PCIe, SATA, Molex) are detachable, offering a balance between cost and cable management.
Power Efficiency Ratings (80 Plus Certification): Power supplies convert AC to DC, and some energy is lost as heat. The 80 Plus certification program rates PSUs based on their efficiency at various load levels (20%, 50%, 100%). Higher efficiency means less wasted power and less heat generation.
80 Plus Standard
80 Plus Bronze
80 Plus Silver
80 Plus Gold
80 Plus Platinum
80 Plus Titanium (highest efficiency, often 90+\% at low loads)
Redundancy and headroom:
Redundant power supply: Multiple independent power supply units within a system (often found in servers and critical network equipment) that can take over immediately if one unit fails, ensuring uninterrupted operation for mission-critical systems and higher availability. Many are hot-swappable.
Ensure wattage rating exceeds peak load: Always select a power supply with a wattage rating significantly higher than the calculated peak power consumption of all components (e.g., 20-30\%\, headroom) to ensure stability, efficiency, and longevity, especially during bursts of high activity from the CPU and GPU. This provides a safety margin and allows for future upgrades.
Modular and Redundant Power Supplies (Notes)
Modular power supplies:
Allow selective cabling (CPU/PCIe power, motherboard power, drive power) to keep the case tidy and improve internal airflow by eliminating unnecessary cables. This also makes installation and upgrades cleaner and more aesthetic, as only needed cables are present.
Redundant power supplies:
Typically found in enterprise-grade servers and critical network equipment. They provide uninterrupted power in case one unit fails, as a secondary (or tertiary) unit immediately takes over, preventing downtime. Some redundant PSUs are hot-swappable for seamless replacement without shutting down the system.
Common cabling categories shown in practice:
CPU/PCIe cables: Dedicated power lines for the central processing unit and high-power graphics cards or other PCIe expansion cards, often required for modern gaming PCs and workstations.
Peripheral, IDE, SATA/Molex connectors: Provide power to storage drives (HDDs, SSDs, optical drives) and other accessories like case fans, lighting strips, or legacy peripherals.
Uninterruptible Power Supplies (UPS)
Purpose: Provide temporary battery backup power during power outages or fluctuations (like brownouts or voltage sags), and offer surge protection against electrical spikes, safeguarding sensitive equipment from damage and data loss. They allow for graceful system shutdown or continuous operation through brief interruptions.
Typical features:
Battery backup: Provides power for a limited time (minutes to hours, depending on UPS capacity and load) during an outage, allowing for graceful shutdown of systems or continuous operation through brief interruptions.
Surge protection: Absorbs voltage spikes and surges, diverting excess electricity away from connected electronics, thereby protecting them from damage.
Data port for management and signaling: Allows the UPS to communicate with the computer (e.g., via USB or serial cable) to monitor power status, send alerts, trigger automatic shutdowns when the battery is low, and manage power settings through dedicated software.
Types of UPS:
Standby (Offline) UPS: Basic type that switches to battery power only when a power problem is detected. Best for home use or basic electronics where occasional brief interruptions are acceptable.
Line-Interactive UPS: Offers voltage regulation (boosting low voltage and trimming high voltage without switching to battery), providing better protection against power fluctuations. Suitable for small offices and home users with more sensitive electronics.
Online (Double Conversion) UPS: Provides continuous power from its inverter, constantly converting incoming AC to DC to charge the battery, then back to AC for the output. This offers the highest level of protection by isolating equipment from all line disturbances, ideal for mission-critical servers and sensitive equipment.
Brands/examples in study materials (illustrative): APC Back-UPS, CyberPower, Eaton.
Practical use: Protects desktop computers, servers, network equipment, and other valuable electronics from power disturbances. It allows users to save work, finish critical tasks, and shut down systems properly during an outage, preventing data corruption, hardware damage, and loss of productivity.
Quick Reference: Key Terms and Concepts
NVMe: Non-Volatile Memory Express; a high-performance communication protocol specifically designed for SSDs, leveraging the PCIe bus for maximum speed, lowest latency, and high parallelism.
SATA: Serial ATA; a common interface for HDDs and SSDs, connecting them to the motherboard for data transfer. Limited to 6\ \text{Gbps}, which can bottleneck faster SSDs.
PCIe: Peripheral Component Interconnect Express; a high-speed serial expansion bus used for connecting expansion cards (like GPUs, NICs, and NVMe SSDs) directly to the CPU or chipset, offering significantly higher bandwidth than SATA.
M.2: A compact motherboard slot and form factor for SSDs and other expansion cards, supporting both SATA and PCIe (NVMe) interfaces and coming in various lengths (e.g., $2280$) and keying (B, M, B+M).
mSATA: Miniature SATA; a smaller form factor for SSDs, primarily found in older compact devices, using the SATA interface protocol. Largely replaced by M.2.
RAID: Redundant Array of Independent Disks; a technology that combines multiple physical disk drives into a single logical unit for data redundancy, performance improvement, or both (e.g., RAID 0 for speed, RAID 1 for mirroring, RAID 5 for parity, RAID 10 for combined speed and redundancy).
HBA: Host Bus Adapter; a circuit or card that provides an interface between a computer's host system and a storage device (e.g., a SATA controller or dedicated RAID card).
PATA: Parallel ATA; an older, slower HDD interface that uses wide ribbon cables, largely superseded by SATA due to speed and cable management limitations.
Boot/driver flow: The typical sequence for installing a new hardware component: physically install the card (ensuring proper slot, power, and ESD precautions), boot the computer, install the appropriate drivers (either automatically via PnP or manually from vendor software for optimal performance), and use BIOS/UEFI settings for advanced configuration or troubleshooting as needed. Always consult documentation.
Hot-swappable: The ability to safely connect or disconnect a device (e.g., a USB drive, a redundant power supply unit, or certain RAID drives) to/from a running system without needing to power down or reboot, provided the OS or controller supports it.
Equations and Numeric References (LaTeX)
Drive speeds: \text{Speed} = \text{rpm} where rpm \in {5400, 7200, 10000, 12000, 15000} revolutions per minute for HDDs.
Power rails (example): \mathbf{V{\text{out}}} = {V{3.3} = 3.3\,\text{V}, V{5} = 5\,\text{V}, V{12} = 12\,\text{V}} commonly supplied by ATX power supplies.
Input voltages: \mathbf{V_{\text{in}}} = {115\,\text{V}, 220\,\text{V}} (common nominal AC input voltages).
SATA 3.0 speed: \text{Max Speed} = 6\ \text{Gbps} \approx 550\ \text{MB/s}.
PCIe Lane Speed (approximate):
PCIe 3.0 per lane: \approx 985\ \text{MB/s}
PCIe 4.0 per lane: \approx 1.97\ \text{GB/s}
RAID levels (conceptual):
\text{RAID}_0: \text{striping (performance)}
\text{RAID}_1: \text{mirroring (redundancy)}
\text{RAID}_5: \text{striping with parity (fault tolerance)}
\text{RAID}_\text{10}: \text{mirrored striped sets (performance and redundancy)}
Connections to Real-World Relevance
Choosing the right storage depends heavily on performance needs (e.g., NVMe for high-speed applications like gaming or content creation), capacity requirements (considering cost per GB for HDDs vs. SSDs), and fault tolerance (decided by RAID levels for data protection in servers or critical workstations).
NVMe over PCIe provides the best performance for modern workloads like gaming, content creation, and highly demanding applications, while SATA SSDs offer a cost-effective balance of speed for general computing and upgrades to older systems.
Proper power budgeting (ensuring adequate wattage and considering efficiency ratings via 80 Plus certification, along with redundancy with redundant PSUs and UPS) is essential for system reliability, particularly in servers, workstations with multiple GPUs, or systems with numerous drives. This prevents unexpected shutdowns, component damage, and ensures stable operation under load.
Understanding form factors (2.5'' vs 3.5'' for HDDs, M.2, mSATA for SSDs) is crucial for ensuring physical compatibility when buying or upgrading components for various devices like laptops, desktops, thin clients, and embedded systems.
Upgrading or configuring expansion cards requires careful attention to resource allocation (IRQ/DMA considerations, vital for legacy hardware but mostly automated by PnP), proper BIOS/UEFI settings (e.g., disabling integrated graphics for a discrete GPU), and installing correct, up-to-date drivers to ensure devices function correctly, the system remains stable, and full performance is achieved.
Foundational Principles Touched
Plug and Play (PnP) greatly simplifies hardware installation by automating resource allocation, but understanding underlying resource management concepts (IRQs, DMAs, I/O addresses) can be vital for troubleshooting older or specialized hardware where conflicts might arise.
The distinction between HDDs and SSDs represents a fundamental shift in storage technology: mechanical (spinning platters, moving heads) vs. solid-state (flash memory), with distinct trade-offs in terms of speed, durability, power consumption, noise, and endurance (write cycles). This highlights the evolution of computer architecture from electromechanical to purely electronic components for increased efficiency.
System reliability is significantly enhanced by implementing redundancy measures (such as RAID configurations for data protection, redundant power supplies for hardware fault tolerance, and Uninterruptible Power Supplies - UPS - for protection against power interruptions) and the ability to gracefully handle power outages to prevent data loss and hardware damage. This underscores the importance of backup and fail-safe strategies in robust system design.