What Type of Computer Memory You Need - dummies

What Type of Computer Memory You Need

If you want to upgrade your computer’s memory, you need to know what kind of memory it needs. Here are two methods to determine which type of memory modules your current motherboard requires and which memory speeds it can handle:

  • Check the specifications. Refer to the motherboard manual. Or, if you purchased your PC from a manufacturer, check the documentation that accompanied the computer.

    If you didn’t get any manuals with a used PC, visit the company’s Web site for memory compatibility information or specifications.

  • Check the existing modules. If you can’t find any documentation, specifications, or data on the Web concerning your PC’s RAM modules, it’s time to remove the case from your computer. Look for the memory slots on your motherboard.

Your PC probably sports one of these types of memory:

  • DDR: Double data rate (DDR) modules were the first 168-pin standard Dual Inline Memory Modules (DIMM) available for PCs; DDR modules are still in general use.


  • DDR2: DDR2 modules double the data transfer rate between your RAM and your motherboard, providing the best performance around, but they basically look the same as a DDR module.

  • RDRAM: Rambus (RDRAM) modules are much faster (and also more expensive) than standard DDR modules. DDR2 has largely taken RDRAM’s place.

  • SDRAM: SDRAM (sometimes called SyncDRAM) takes the form of standard 168-pin DIMMs. SyncDRAM runs at an access speed of 133 MHz, which is too doggone slow for today’s fast processors.


  • EDO: Older Pentium motherboards used Extended Data Output (EDO) memory in the form of 72-pin Single Inline Memory Modules (SIMMs).


If your PC has EDO memory modules, your PC is so far behind the performance of new models that it just isn’t worth adding EDO memory to your older motherboard. Just upgrade your CPU, motherboard, and memory at the same time.