RAM

What is DIMM?

Dual In-line Memory Module

• The standard full-size ram stick used in desktop motherboards

What is the standard data bus width of DIMM?

64-bit

How many pins do DDR4 and DDR5 have?

DDR4 and DDR5 have 288 pins

How many pins does SODIMM DDR4 have?

260

How many pins does SODIMM DDR5 have?

262

What is SODIMM?

Small Outline Dual In-line Memory Module

• The RAM form factor used in laptops, compact desktops, and some printers

How do you distinguish DIMM from SODIMM physically?

DIMM is the full length desktop stick. SODIMM is roughly half the length and is used in laptops

What does DDR stand for?

Double Data Rate

What is the key feature of DDR?

Transfer data on both the rising and falling edges of the clock cycle

• Effectively doubles bandwidth when compared to single data rate

What does each successive DDR generation bring?

Each generation of DDR brings higher speeds, lower voltage, and more bandwidth

What is the difference between DDR4 and DDR5?

• DDR5 Doubles the memory banks groups per module

• Starts at much higher speeds (4800 MT/s vs 2133 MT/s)

• Uses low voltage (1.1V vs 1.2V)

How do DDR generations prevent incorrect installation?

Each DDR generation has a different notch (key) position on the module’s edge connector

• This key ensures a DDR5 stick cannot be inserted into a DDR4 slot.

What does MT/s mean in the context of RAM speed?

MT/s is the data transfer rate in megatransfers per second

What is ECC RAM?

Error-Correcting Code RAM

• detect and correct single bit memory errors on the fly using extra chip(s) on the module

Where is ECC RAM commonly used?

In servers, workstations, administrative critical systems where data integrity is paramount

What requirements are there for using ECC RAM?

Requires ECC capable CPU and motherboard support

What is non-ECC RAM?

Standard RAM without error-correction hardware

• less expensive and used in consumer desktops and laptops

What happens to the ECC-RAM on a motherboard that does not support ECC-RAM?

The ECC RAM should still be recognised and function, just no error-checking

What a happens when you insert non-ECC RAM into a motherboard that supports ECC?

The non-ECC RAM can damage the ECC functionality of the motherboard

What is single-channel configuration?

It is when one memory stickers installed

• Data travels on a single lane

What is dual-channel memory configuration?

Two matching memory sticks installed in the correct order

• This doubles the number of lanes

• Can travel on both sticks simultaneously, speeding up communication

What is quad-channel memory configuration?

Requires four matching sticks

• it allows for multiple lanes (channels)

Where do you commonly find multi-channel memory implementations?

They are used in high-end workstations and servers

What happens if you mix RAM speeds in the system?

The system will typically run all sticks at the speed of the slowest stick

• It may also fall back to single channel if sticks are mismatched or placed in the wrong slots