Cas Latency

[Rody]

If there is something about hardware Im still unaware these days is RAM Cas Latency, I'm going for some upgrades today Im geting dual channel 400Mhz ram 2x256 probably to be used with a Intel 865PE chipset motherboard and P4 3Ghz FSB 800 (prescot or northwood???? Im still with this question in my mind ). So how should i choose my ram and its cas latency speeds?

[jd53887]

everypone is gunna tell you to either get a gb of rams, get better rams (like PC3500 with low latency), and the northwood cuz it;s cooler. If you can cool your computer good enough, go with the prescott I guess. If you r going to be OC'in go for the Northwood and the PC3500 so you have more head room for OC'in.Any rams you get that has a cas of 2 should be good. Unless you get the OCZ EB where it's not about the CAS, but the bandwidth.

[Yawgm0th]

I'd say you should go with an AMD setup...

As for CAS latency, you'll basically have choices between 2, 2.5, and 3 (anything higher would be pretty bad). The lower, the better. There are other parts of RAM latency as well. RAM will usually be advertised with latency numbers like so:
CAS-tRP-tRCD-tRAS
The lower the first three numbers, the better. The fourth number, tRAS, should be at least CAS + tRCD + 2. Ignore the advertised tRAS of any RAM and set it at least that high, if you can. Many RAM modules will come advertised with inproper tRAS because of the common misconception that lower tRAS means more performance.

Anyway, it's not absolutely necessary to get low latency RAM. It's best to do if you aren't overclocking. If you are overclocking, it can be smarter to get RAM rated for higher speeds (or OCz Enhanced Bandwidth as it overclocks extremely well), but with worse latency. Also, it's not necessary to go buy expensive low latency modules. You can spend over twice as much on the same amount of RAM if you buy RAM with 2-2-2 timings. With that money, you could have simply gotten a faster processor with worse RAM, which would perform much better. Having 2-2-2 instead of 2.5-3-3 won't mean as much as getting a processor that's 400MHz faster, especially if you are talking about AMD (particularly Athlon 64) processors, which is what you should get for just about anything except a machine meant only for video encoding. However, some of the extremely expensive modules overclock extremely well, so it can still a good idea to get them if you intend to overclock a lot.

If you are going for heavy overclocking, I would recommend Crucial Ballistix PC3200, OCZ PC3700 EB, or OCZ PC3500 EB.

If you aren't overclocking or aren't focusing on overclocking, stick with something cheaper. Corsair PC3200 with 2-3-3 timings would be good.

[Rody]

Thanks for the suggestions !
Well as I'm not OC'in I got the 3.0 prescot with the 875 chipset and the Corsair 3200 memory.

PS:I'm very happy with the performance