|Computer memory comes in standard modules, but there are several standards and you must be careful to order the correct type of memory for the motherboard or SBC in your computer.
DIMM is the common name for a memory stick. Memory comes in several pin counts, and you can only use memory with the correct number of pins in a particular machine. Note that older memory DIMMs are made in 30-pin, 72-pin, and 168-pin sizes, while most newer machines use 184-pin DDR DIMM modules, and now 240-pin DDR2 DIMM modules. Many notebook PCs commonly use SODIMM 144-pin modules, while newer notebook PCs use 200-pin DDR SODIMM modules.
Memory is also available in different speeds, which determines whether the memory can keep up with the speed of your computer. Please check your owner's manual or contact the manufacturer of your computer to determine the minimum memory speed your PC requires. It is a good idea for all the memory modules in your computer to be of the same speed.
Memory speed has been stated in several ways over time, but usually by the same standard for a particular memory type. For example, DIMM modules are commonly stated as being "PC100" or "PC133" speed, while DDR modules are rated as "PC2100" ("PC2700," "PC3200," etc.) or they are shown as "266MHz" ("333MHz," "400MHz," etc.). If the speed needed for your system is no longer available, faster speed memory should work without a problem - your PC simply won't push the new memory to it's fullest capability.
ECC memory is generally used only by servers. Most PCs use non-ECC memory, and most of the memory we sell is non-ECC memory.
As a general rule, motherboards and SBCs using Pentium® 4 or Athlon® XP processors use DDR memory modules (184-pin for desktop PCs, 200-pin for notebook PCs). Pentium II, Pentium III, Celeron®, Duron®, and Athlon systems usually use 168-pin DIMMs (144-pin SODIMMs for notebook PCs). Older 486, 5x86, Pentium, and Pentium MMX systems (under 233MHz) usually use 72-pin DIMMs, though these have become rare.