[Thermodyne]

Fyron hit it on the head. The board determines the memory type and speed. Most boards will support several speeds and adjust the buss automatically. Some boards will allow you to set the voltage and buss speed above the specs for the installed ram.

SDRAM fits lots of older systems regardless of CPU.
DDR fits lots of currant systems regardless of CPU.
DDR II fits Intel only.
RDRAM fits Intel only.

All of the types come in standard, EEC and Registered EEC. EEC is for high end workstations and servers. Registered EEC is for high end servers and required for some AMD CPU’s.