General Information about Computer Memory (RAM)

There are many different types of memory and this page is by no means a complete dissertation on the various types of memory you will find in computers or printers. For more detailed information, Kingston Technologies has a lot of very good information. I use their site to lookup which memory is needed for a specific device.

Adding Memory to a Computer

The first thing is to lookup what memory has been tested for the computer on the manufacturer’s website. If that cannot be found Kingston has a memory lookup tool that covers most computer’s memory configuration.

When adding memory to a computer all of the memory needs to be the same speed (i.e. PC133, PC3200, etc...) and have the same CL number (Column Access Strobe Latency i.e. CL2, CL3, etc...) or the computer will be unstable.

DDR Memory Naming Conventions

Double Data Rate (DDR) SDRAM Double Data Rate (DDR2) SDRAM
DDR 266MHz PC2100 400MHz DDR2 PC2-3200
DDR 333MHz PC2700 533MHz DDR2 PC2-4200
DDR 400MHz PC3200 667MHz DDR2 PC2-5300
    800MHz DDR2 PC2-6400
    1066MHz DDR2 PC2-8500
Double Data Rate (DDR3) SDRAM  
DDR3 1066MHz PC3-8500    

Identifying Older Memory

The first step in determining what type of memory your system uses is by looking for a manufacturer's part number. The better memory manufacturers will normally attach a label to the memory stick. If there is no label and you have no clue what type of memory you have you can start by measuring the length of the memory.

Physical 30-Pin SIMM, 72-Pin SIMM, and 168-Pin DIMM Sizes


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