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DDR2 800 vs DDR3 1333

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August 25, 2010 6:29:27 PM

Hello,
I am planning to replace my 3 year old computer. Currently my e6750 runs on DDR2 800 with CAS 5.
Since I'm planning to get the i7-870, I was looking at 1333Mhz sticks.
Can someone tell me if this calculation is any good:
800Mhz CAS4 = 1/400 = 2.5ns/tick = 12.5ns/transfer

1333Mhz CAS 9 = 1/666 = 1.5ns/tick = 13.5ns/transfer

I find it very hard to believe that DDR2 beats DDR3. So what am I missing here !?

More about : ddr2 800 ddr3 1333

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a b B Homebuilt system
August 25, 2010 6:42:51 PM

You are comparing low latency DDR2 with high latency DDR3. It would be more fair to compare your old RAM with Cas 7 DDR3-1333. There might be some archetecture advantages also. In any case the jump from DDR2 to DDR3 is not that big of a deal. You also dont have any choice so it doesnt really matter.
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a b B Homebuilt system
August 25, 2010 6:47:54 PM

http://en.wikipedia.org/wiki/CAS_latency - see the additional links for more.

It looks like your math is close, but as dndhatcher points out, 800 MHz CAS 4 is pretty much top of the line DDR2, while 1333 MHz CAS 9 DDR3 are bargain bin sticks (mostly). Comparing to CAS 6 or CAS 7 would be a more appropriate comparison.
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August 25, 2010 7:53:26 PM

Oops, I mistyped Cas4. It's supposed to be Cas5 (as reflected by the math).

Thanks for the quick replies. I could've sworn I spent about the same $$ 3 years ago for the 800Mhz sticks. I guess this side of technology did not progress that much.
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August 25, 2010 7:54:13 PM

Best answer selected by divac.
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