📖 IT Bible

Memory Modules and RAM Types

(OBJ 3.3)

Memory Modules are identified by:

  • Type (ie. DDR3, DDR4, DDR5)
    • DDR (Dual Data Rate) most common type of memory used in most systems
  • Size
  • Speed

Banks

  • Single Bank - can put any size of module in any slot
  • Paired Bank - requires installation of bank parts

Larger Motherboard = more memory slots

DIM (Dual Inline Memory)

PC133 has a bus speed of 133 MHz

Throughput - calculated based on bus speed and the width of the data bus

Types of RAM

  • DRAM (Dynamic RAM) - oldest type of memory that requires frequent refresh
  • SRAM (Static RAM) - solved the issue of the constant refresh, but expensive to manufacture
  • SDRAM (Synchronous RAM) - first memory module that operates at same speed as motherboard bus
  • DDR SDRAM (Double Data Rate Synchronous Dynamic Random-Access Memory) - doubles transfer speed of an SRAM module (184 pin connector)
  • DDR2 SDRAM - higher latency and faster access to the external bus (240 pin connector)
  • DDR3 SDRAM - runs at lower voltage and higher speed than DDR2 (240 keyed pin connector)
  • DDR4 (Double Data Rate Version 4)
  • DDR5 (Double Data Rate Version 5)

It’s recommended to buy modules in pairs when using multiple modules of same brand, speed and throughput

Sizes of RAM

  • SODIMM (Small Outline Dual In-Line Memory Module) - classified as DDR3, DDR4, DDR5