memory latency

[JohnJH05]

i have a p4 2.8 with a IS7 mobo. for memory i was looking at kingston hyperx (@x512) which had a cas latency 2. do i really need this latency? or can i go with a higher one? whats the difference? just tell me about it cuz i dont know much about it. thx

 

[MichaelD]

Memory latency is measured in Nanoseconds (billionths of second) Lower is better.

CAS latency refers to how many nanoseconds it takes for the memory to execute an instruction. My exact terminology may be wrong, but the idea is right. 😉

Lower is always better. Don't skimp on memory; you'll regret it down the road. Cheapmemory is cheap for a reason. Get good stuff and not only will you not regret it, but you can use it in other systems down the road.

 

[Shooters]

Actually I believe latency is measured in clock cycles, not nanoseconds.

Anyway, some people prefer low latency memory because it allows them to overclock higher. For example, you could probably expect a PC3200 CAS 2 module to overclock higher than a PC3200 CAS 2.5 module from the same manufacturer (of course overclocking is never a sure thing, so this won't always be true). But, if you're just running at stock speeds, then I see no real reason to go with low latency modules unless of course the price difference is small or you just have money to burn. I've always heard that the performance difference on average between CAS 2 and CAS 3 is somewhere around 3-5% depending on the application, so you can expect the difference between CAS 2 and CAS 2.5 to be even smaller. Sure, you may see a small difference in benchmark numbers, but anyone who says they can "feel" the difference is BS'ing. Also, remember that sometimes there will be no performance difference at all.

I say, if you need the overclocking headroom, then go for the CAS 2, but if you don't, then just save your money.

 

[egale]

After just putting together a p4 3.0c with an Asus P4C800-E mobo and Corsair 1G twinxx 3200LL, I can tell you that the timings will make very little difference. I played with the timings and found the differences minimal in benchmarks and unnoticeable anywhere else. Where you will see big performance increases is with fsb settings. If you can run the fsb at 210 instead of 200, you then start to see real performance increases.