Due to the high number of instances of memory problems/questions on which ram to buy I am putting together a Guide.
First, you need to know that the high end Asus boards are picky when it comes to RAM. If you want to be safe get something on the QVL or something that many people are using with success with your board/CPU combo.
Next, Do not limit your overclock by buying 1333Mhz or lower ram! Even 1600Mhz RAM may limit your overclock. This is due to the limited number of dividers.
Now if you have a black edition CPU you can overclock with Multiplier only. Cool, but you will not see the memory throughput of someone that overclocks the FSB will if IMC/CPU-NB speeds are the same and Core speeds are similar. This is because there are two main bottlenecks with systems that are dual channel. The first being the FSB and the second being the IMC/CPU-NB speeds.
On to timings, Timings also play a big role in memory throughput, and you will see big changes when going from certain latencies to others. For me when I go from cas 7 to cas 6 I see a HUGE increase in throughput. However when I go from cas 8 to 7 I see very little difference.
IMC/CPU-NB limits, I can run 2000Mhz 7-9-7-24 but can not get much of an overclock on my IMC/CPU-NB. If I run 1600Mhz with a IMC/CPU-NB overclock I can see greater throughput then when running 2000Mhz. This is due to the IMC/CPU-NB bottleneck.
All in all when selecting RAM there are four things to look at.
1.) Are they confirmed compatible
2.) Is the RAM speed going to hold me back
3.) Are the timings decent.
4.) Is the voltage decent.
One is easy, look at the QVL or other members rigs.
Two is easy as well you should be looking at ram that is above 1600Mhz IMHO 2000MHz+ is where you want to be.
Three, decant timings vary upon memory speed. cas 9 is insane nowadays even for 2000Mhz RAM.
2000Mhz look for cas 7 or 8
1800Mhz cas 7
1600Mhz cas 6
anything lower and you are wasting you time.
Formula Tested RAM:
Extreme Tested RAM:
I am going to be editing this guide to include links as well as the QVL's for both boards. If you see anything that you think needs work let me know! (PM's please, dont clutter the thread.)Edited by eclipseaudio4 - 1/21/11 at 7:52pm