I've got a 750W if I remember correctly.
At first I would have my mem voltage set to auto. However, I called corsair and they said make it 1.9v which it is at now.
I'm not really sure what to change my timings too, only due to the plethorea of options. Such as tCS, and I am not really 100% sure about what I should change.
I know for my 4GB, the timings are 5-5-5-18 or whatever. All 5's until last one is 18. And the voltage for that is 1.9v. However, once again, too many options for changing things, which of the many options should I change (tCS, or whatever them are called)? Thanks.