What am i missing here?

[OSB]

I know i must be mis-understanding something here. The current processors, looking at the E6xxxs even when OC'd have FSBs of around 400-500mhz. Now most people seem to run this at 1:1 with thier RAM, usually pc6400 which is rated to 800mhz! Surely this is totally excessive and why would we then need RAM with timings all the way up to 1000mhz if we are only using 1:1? Is there some doubling thing with the FSB which i have forgotten about? Thanks for clearing this up for me!!

 

[Zefan]

Is there some doubling thing with the FSB which i have forgotten about?

Yup. Don't ask why though, I have no idea

 

[OSB]

heh thought so! The why was kinda what i was hoping for though! curious bloomin youth

 

[Cob]

DDR = Double Data Rate. It runs the RAM at twice the FSB rate of the processor.

 

[[timko]]

I know i must be mis-understanding something here. The current processors, looking at the E6xxxs even when OC'd have FSBs of around 400-500mhz. Now most people seem to run this at 1:1 with thier RAM, usually pc6400 which is rated to 800mhz! Surely this is totally excessive and why would we then need RAM with timings all the way up to 1000mhz if we are only using 1:1? Is there some doubling thing with the FSB which i have forgotten about? Thanks for clearing this up for me!!

When you see adverts from ram that "Runs at 800Mhz t3h w00t omfg!!!One1Eleven" they are actually referring to the data rate, which is double hence Double Data Rate. The *actual* speed the RAM stick is running at is half. See this...

Sticks/Modules
PC2-3200: DDR2-SDRAM memory stick specified to run at 200 MHz using DDR2-400 chips, 3.200 GB/s bandwidth
PC2-4200: DDR2-SDRAM memory stick specified to run at 266 MHz using DDR2-533 chips, 4.267 GB/s bandwidth
PC2-5300: DDR2-SDRAM memory stick specified to run at 333 MHz using DDR2-667 chips, 5.333 GB/s bandwidth1
PC2-6400: DDR2-SDRAM memory stick specified to run at 400 MHz using DDR2-800 chips, 6.400 GB/s bandwidth

http://en.wikipedia.org/wiki/DDR2_SDRAM

So when someone says they're running an FSB of 400Mhz 1:1 with their ram, the ram is also running at 400Mhz but the effective data rate is 800Mhz. Here is where a stick of PC2-6400 running at stocks speeds, no ocing, would be ok because it specified to run at 400Mhz actual and 800Mhz effective.