fsb and memory question

[gobeavers]

This may be stupid, but with syncing the fsb and memory, or with the ratios. Lets say in a 800 p4 and DDR 400, is it the effective rates have to be syncronous, qdr 800 and ddr 800, or do the regular speeds have to be syncronous, or ratioed, 200 and 400. I am assuming the first is correct, but I want to be sure.

 

[pIII_Man]

you have to relise that although intel and amd say there bus speeds are XXX fast...they really are not...

The actual frequency of the FSB on an intel machine that uses an 800mhz claimed fsb is 200mhz...QDR does not mean 4x the speed...it means 4x the info can pass per clock cycle

the actual frequency of ddr400 (pc3200) memory is 200mhz...again it is double DATA rate...therefore manufactuers are just trying to wow and pow the buyers

the only way to theoretically sync a 200mhz qdr bus to a 200mhz ddr memory bus in such a way that the max bandwith of the qdr bus is being used is to run pc3200 (400mhz ddr, 200mhz sdr) in a dual channel arangement thus the bandwith of the two will be equal...
ddr bandwith (pc 3200)
16bits x 200 = 3200
qdr bandwith (on 800mhz fsb intel cpu)
32 x 200 = 6400

thus you can see if we had a dual channel memory controlor the qdr and ddr buses would be synched with pc3200 ram


So easy to fry yet tastes so good...
Silicon: The other, other, other white meat

 

[gobeavers]

thanks for the explanation.<P ID="edit"><FONT SIZE=-1><EM>Edited by gobeavers on 07/28/03 00:40 AM.</EM></FONT></P>