what is the difference between ddr?

[HOTxSHOT]

what is the difference bettwen pc2700 ,pc2400 and so one?

i have this board M7SXF PGA 478 Pentium® 4 Desktop Board, 400Mhz FSB, 3 DDR DIMM, Sound, but i dont know which kinda of ddr it will accept... can anyone help?

 

[AndyHui]

Those are simply ratings for guaranteed maximum speed.

Reading these two FAQs may give a better understanding of how RAM works:

What is DDR SDRAM?

RAM Considerations