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FSB and RAM ratio

Last response: in Memory
September 28, 2008 3:39:45 AM

I want to make sure I calculate this ratio correctly...

If I have a 1066 FSB CPU and DDR2-800 ram, the ratio would be (1066/4 : 800/2) = 266:400 ?
What does this mean exactly? Are these not compatible?

I'm a novice builder, bear with me.

More about : fsb ram ratio

September 28, 2008 4:09:48 AM

you can always read the sticky given in these forums for your specific purposes

there compatible, your just running them at a 2:3 ratio... its perfectly fine, most people like running them at 1:1 as myself, lowering the speed of your ram from 800 to 667, but tightening timings... people get different results with this kinda stuff
September 28, 2008 4:39:16 AM

But does this mean that the fastest memory I should buy for this CPU is DDR2-533?
And basically anyting faster and expensive would be just a waste of money (if Im not overclocking the FSB)?
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September 28, 2008 5:41:33 AM

yes your FSB is 266

the fsb:mem are able to run at different speeds becuz of the ratio
so as above poster stated, it is a 2:3 ratio

no point in buying slower memory, the faster stuff (800) is the around the same price and if you ever want to move the mem to a diff system that happens to need faster mem, you wont have any issues
September 28, 2008 2:42:52 PM

Hi, I just wanted to follow up on this question with my own.

I was planning on getting 8GB of 1066mhz DDR2 RAM to go with a Intel Q9550 on a P35 motherboard. The system is primarily for virtualization and I don't plan on overclocking.

Given no overclocking, does the FSB/RAM ratio even matter?

The other issue I have a question about is most P35 mobos only seem to support 800mhz DDR2, although the ASUS P5K SE (and maybe some others?) say they support 1066mhz DDR2. Do they really? Or just I just stick to 800mhz RAM (or 667 for 1:1 FSB ratio)?

I really appreciate any and all responses. This is the first system I'm building myself and the first time I've had to "choose" a motherboard. Thank for the help!