Memory Modules

---

A memory module is a printed circuit board that holds a group of RAM devices that act as a single unit.

• produced in different capacities
• Each DDR generation sets an upper limit on the maximum possible capacity

Desktop RAM – DIMM

• DDR for desktop system memory is packaged in a form factor called dual inline memory module (DIMM)
• The notches (keys) on the module’s edge connector identify the DDR generation (DDR3/DDR4/DDR5)
  • prevent it from being inserted into an incompatible slot or inserted the wrong way around
• DDR DIMMs typically feature heat sinks, due to the use of high clock speeds

Info

• Memory slots look similar to expansion slots but with catches on each end to secure the memory modules
• Memory modules are vulnerable to electrostatic discharge (ESD)
  • take anti-ESD precautions when handling and storing

• The DIMM’s DDR type must match the motherboard
  • E.g., cannot install DDR5 modules in DDR4 slots
• For best performance
  • the modules should be rated at the same bus speed as the motherboard
• It is possible to add modules that are faster or slower than the motherboard slots or mix modules of different speeds
  • However, the system will operate only at a speed that is supported by all installed components (memory modules and controller)
  • not generally a good idea

Laptop RAM – SODIMM

Laptop RAM is packaged in a smaller form factor called Small Outline DIMM (SODIMM)

• typically fitted into slots that pop up at a 45º angle to allow the DIMM to be inserted or removed