How much impact does memory latency have on proformance?

Chu

Banned
Jan 2, 2001
2,911
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Hello all, I'm currently putting together a Northwod system (Asus P4B board, Intel 1.6a, hopefully running at 2.0 and beyon) and have a question about memory.

First off, this computer is basically always doing some sort of video encoding, and the 2-3 fps I get with my P3 933 is TOO DAMN SLOW. Please keep this in mind when answering my question.

I pretty much need 512 megs of memory because encoding is generally a hog. 512 megs @ 3-3-3 is the base price. 512 megs at 2.5-3-3 would cost me another $30. 512 megs at 2-3-3 is another $20, and 2-2-2 is another $10 yet again. My question is, how much of a difference do these latencies really make? That premium really starts adding up, and I need to know if it's worth it.

Also, a related question. Let's say I buy Mushkin PC2100 3-3-3 sticks. What are the odds this will run at 3-3-3 at 135? 140mhz? 150mhz? Would 2.5-3-3 running 3-3-3@130/140/150 fare better, or would the higher latency cancel out the benefit of the higher CPU and Memory clocks?

-Chu
 

John

Moderator Emeritus<br>Elite Member
Oct 9, 1999
33,944
5
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Cas2 memory will typically add 3~5% over cas3. Most of your quality memory (Crucial, Corsair, Samsung, etc) will be rated @ cas 2.5, but will do cas2 up to 150FSB no problem.