Section 3.5 Power Supplies

What is the standard AC input voltage in North America?

110-120 VAC

What is the standard AC input voltage in Europe and Asia?

220-240 VAC

What does VAC stand for?

Volts Alternating Current

What voltage rail powers most modern CPUs and GPUs?

+12V

What is the purpose of the +5V rail in a PSU?

Powers older components and some USB devices

What is the +3.3V rail typically used for?

Powers motherboard components and some expansion cards

What is the function of a power supply unit (PSU)?

Converts AC power to DC power for computer components

What does a 24-pin power connector provide?

Primary power to the motherboard

What does a 4-pin or 8-pin CPU connector do?

Supplies power specifically to the CPU

What is a 20-pin to 24-pin adapter used for?

Allows older PSUs to connect to modern motherboards

What is a modular power supply?

Allows unused cables to be detached for better airflow

What is a semi-modular power supply?

Some cables are fixed; others are detachable

What is a fully modular power supply?

All cables can be disconnected

What is a redundant power supply?

A backup power unit that activates if the main PSU fails

Where are redundant PSUs commonly found?

Servers and enterprise-grade equipment

What does PSU wattage indicate?

The maximum total power the PSU can deliver

Why is choosing the correct wattage PSU important?

To ensure stable operation and allow for upgrades

What happens if a PSU is underpowered?

System instability, failure to boot, or shutdowns

What tool can help determine power needs?

Online PSU wattage calculator

What is a symptom of a failing power supply?

Random shutdowns or system not powering on

What type of current do PSUs output?

DC (Direct Current)

What connector is used for SATA drives?

15-pin SATA power connector

What connector is used for older IDE drives?

Molex connector

What color wire typically carries +12V in PSUs?

Yellow

What color wire typically carries +5V?

Red

What color wire typically carries +3.3V?

Orange

What color is the ground wire?

Black

What PSU feature helps protect against power surges?

Over-voltage protection

What is the role of active PFC in a PSU?

Improves efficiency and reduces power consumption

What certification ensures PSU efficiency?

80 Plus certification

What does an 80 Plus Bronze PSU indicate?

At least 82% efficiency at 20%, 50%, and 100% load

What is one advantage of a modular PSU?

Improved cable management and airflow

What happens if the wrong voltage is selected on a PSU?

System damage or PSU failure

How do you switch between 110V and 220V input?

Manual switch on PSU or auto-switching in modern models

Why is it important to match PSU connectors to components?

Incorrect connections can damage hardware

What component uses the most power in a typical system?

Graphics card (GPU)

What power connector do high-end GPUs often require?

6-pin or 8-pin PCIe power connector

What is the recommended PSU wattage buffer?

20-30% above peak power usage

Can a PSU be too powerful for a system?

Yes, but it will only use the power required

Why are redundant PSUs hot-swappable?

To allow replacement without shutting down the system

What determines the number of components a PSU can support?

Available connectors and total wattage

What does the 24-pin connector power?

Motherboard and primary system components

What is a sign of an overloaded PSU?

Overheating or system shutdown under load

What safety feature is required by law in PSUs?

Over-current and short-circuit protection

What does the term 'rail' refer to in PSU design?

A voltage output line inside the PSU

What is a single-rail PSU?

One +12V rail powering all components

What is a multi-rail PSU?

Multiple +12V rails with separate current limits

What should be done before replacing a PSU?

Disconnect all power and ground yourself

What is a symptom of incorrect AC voltage selection?

Burned out PSU or failure to start