actual speed of a system with 800MHz or 1033 MHz DDRs

theberserker

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I am getting myself a new computer and I am curious about this thing for ages:
Let's say I have an (Intel) processor and the motherboard working at 1066 MHz. Is in case i have pair of 800 MHz DDR2s speed of system affected at all, because the clocks are not synchronized, or are those values negligible due to RAMs latency? A little explanation (or links) would be much appreciated.

thanks
 

br3nd064

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You won't notice any performance hit. The ram is actually running faster than the cpu is. 1066/4=266 (what the cpu FSB is) 800/2=400 (what ram is running at).

Does that help?
 

theberserker

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It does help. thanks. i understand why DDRs are devided by 2 but now i am confused with 1066/4=266 part. why the frequency's devided by 4?
 

br3nd064

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Intel cpu's are quad-pumped. This means that the actual FSB is 266mhz, but the effective speed is 1066mhz.

For the newer, 1333mhz cpu's, the actual FSB is 333mhz instead of 266.
 

blackwidow_rsa

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Only in dual channel will the ram be fast enough for the fsb. Just get 2 or 4 ram modules and put them in dual channel mode, it should be shown in the motherboard manual if you don't know how
 

theberserker

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oh, yes, it's quad-pumped :blushing: forgot about that already.
of course i will put them in dual channel. so 800 MHz is a good choisce then.

 

compucare

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I am just thinking: why not go with PC 4200, 533Mhz Memory? 533/2 is 266MHz, which is perfect for 1066Mhz CPU(right?) why all the hoopla about PC6400, when it's going to under-clock it (from 400 to 266) anyways?