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I do a lot of gaming on my machine, and have the option of running

  • PC6400 (800mhz) with 4-4-4-12 timings
  • OR PC8000 (1000mhz) with 5-5-5-15 timings.

Which memory configuration will benefit intensive gaming more?

FYI, I have a Wolfdale C2D @ 4.5ghz and GTX-280 SLI if that matters.

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up vote 1 down vote accepted

I would lean toward the one with the higher frequency being faster but generally they will be nearly identical in speed.

for example the

800mhz /12 is 66.66 cycles 1000mhz /15 is 66.66 cycles

800/4 = 200 cycles 1000/5 = 200 cycles

so you can see they should be close to the same speed although in my experience the higher mhz is more flexible with overclocking

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This is incorrect. They won't be the same speed at all. They will have the same latency, but the one with the higher clock speed will transfer data at a higher rate. (For two identical transfers, once the latency time for an operation has passed, the one with the higher clock speed will transfer the data at a faster rate.) – David Schwartz Feb 23 '12 at 20:31
@DavidSchwartz Well that makes sense. – WalterJ89 Feb 24 '12 at 3:47

I think you're forgetting that the latency timings are in cycles.

PC6400 (800mhz) with 4-4-4-12 timings

This RAM has an 800MHz effective clock speed (400MHz actual) and a 4 cycle CAS latency. 4 cycles at 400MHz is 10ns. 12 cycles is 30ns.

OR PC8000 (1000mhz) with 5-5-5-15 timings.

This RAM has a 1,000MHZ effective clock speed (500 MHz actual) and a 5 cycle CAS latency. 5 cycles at 500Mhz is 10ns. 15 cycles is 30ns.

So they have the same latency and one has a higher clock speed. It's a no brainer, the second one wins.

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