CAS Latency of the ram for my new custom pc?

Question

if my pc is going to have 4 gb of dual channel ram( i have 4 slots), what woul be faster:

1) 1gb x 4 at 4-4-4-12 800mhz
2) 2gb x 2 at 5-5-5-15 800mhz
3) 2gb x 2 at 5-5-5-12 800mhz

Answer 1

With 4 GB of new RAM, I would hope you were installing an x64 version of Windows because the x86 (32 bit) versions will never "see" more than 3 GB. To answer this question, the 4-4-4-12 would be faster, naturally, but if you go with the 2GB sticks rated for 5-5-5-12, then you could later buy another 2 sticks of the same RAM and then have a whopping 8GB. I run 4 GB in my system using 4 x 1GB because at the time I bought it, the 1GB sticks were cheaper. I now wish I had gotten the 2GB sticks because I am wanting more.

Answer 2

Well it would appear the 4-4-4-12 would be faster, but there is another problem to consider. Benchmarking has shown that when you run RAM of the exact same speeds, one in a 2x2 configuration, and the other in a 4x1 configuration, the 2x2 configuration is faster. Having to use all four memory slots does in decrease performance when compared to using just two slots. Now of course this decrease would be offset by the fact that the 4x1 are faster to begin with in your case, but whether that would overcome the decrease involved by using all four slots, I have not seen any numbers to answer that question. I would go with option 3, this also has the added benefit of leaving room for a future upgrade.

And of course as already mentioned, make sure you are runninga 64 bit OS.