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Okay, how does Corsair DDR2 6400 work?

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ghost_recon88

Senior Jedi Master
Joined
Feb 12, 2005
Location
Michigan
If I understand correctly, it runs at 800MHz. That means the FSB on your CPU must be running at 400MHz right? If so, that means your actual FSB once it's quad-pumped would be 1.6GHz right? Also, as far as the multiplier goes, 15x appears to be the lowest for a P4. Take 400x15=6000MHz. I don't think anyone has hit that high before. I see in some BIOS it allows you to run RAM 200% faster than your FSB, so for example, if your FSB was 200MHz, the RAM would run at 400MHz but since it's DDR, it would run at 800MHz? Can someone please clear this up for me. I didn't think RAM could ever run faster than the FSB of your CPU but DDR2 6400 seems to make me thing just the opposite.
 
just because it can run that fast, doesn't mean that it will run that fast, DDR2 just makes the processor the limiting factor in overclocking.
 
You have to run the memory faster than FSB. The newest Intel chipsets that use DDR2 RAM allow this option. For example, I have a screen shot of my system running at DDR2-800. I used 300 FSB and the 3:4 ratio. Ignore the quad pumped system bus when figuring up memory speed. By the way, the lowest multiplier on P-4 CPUs would be 14X.
 
batboy said:
You have to run the memory faster than FSB. The newest Intel chipsets that use DDR2 RAM allow this option. For example, I have a screen shot of my system running at DDR2-800. I used 300 FSB and the 3:4 ratio. Ignore the quad pumped system bus when figuring up memory speed. By the way, the lowest multiplier on P-4 CPUs would be 14X.

So, since your FSB is 300MHz and you have the divider at 3:4, the RAM is running at 400MHz but since it's DDR, it's running at 800MHz? Very slick :p
 
Yep, you got it now. Here is the screenie I was talking about. Had to use very loose timings to hit DDR2-800 though.

KHX5400-cpuz-max.JPG


But, if you want lower latencies, then check out my OCZ EB rev2 PC2-4200 with amazingly tight timings.

OCZ-EB-cpuz-tightest.JPG
 
Wait, you hit DDR-6400 speeds with your DDR-4200? Still, if I could hit that even with those loose timings, I think I would. Corsairs timings are 5-5-5-15 and yours are way better.
 
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