Are the sticks from one kit?
You should run a memtest to see if that helps. I'm in a bit of a pickle with memory myself but my blues creens happen a lot less consistently than yours - it could be a whole day before it happens, but I'm 90% certain it's because I'm using a 12GB kit that I bought for my i7 920 (Socket 1366) + a new 4GB stick I bought for this build to bring it to 16GB. I took the chance because I am on a budget knowing full well that it could very easily be a bad match. I had one just about an hour ago, "IRQL_NOT_LESS_OR_EQUAL." That was 20 or so minutes after 2 hours of stress testing + HD video encoding (simultaneously) with nothing going wrong, when I had stopped the tests and decided to watch a TV show that I'd downloaded.
So run memtest86 or memtest86+. Do as many passes as you can, perhaps overnight when you don't need your computer. If you do like maybe 3 passes and there are no errors, perhaps something happened to your Windows 7 install and a repair install or reinstall could fix it. But try the memtest first overnight to see. I passed my tests but I didn't run multiple passes as I had no time. I'd say if I let it run through much longer it would come up with something but the fact that one pass didn't parallels the theory that if it takes sometimes a day to blue screen that the instability isn't as severe as it could be, but minor instability is still instability. So give it a go and see how your system fares.
