multiple sticks or ram causing bsod

Hi,
i built my computer a couple months back, i purchased two sticks of ram, one was faulty and i am sure of that. I recently purchased another, identical kit. I am having problems now when i use more then one stick at a time. I can use any one of the three sticks in any one of the slots (i thought my slot 1 was damaged at one point). I went through the bios, the ram is 1.8-2.0v, ut was set to 1.8 so i upped it to 2. it also sets to 667mhz as default for compatibility when installing and instructs you to up it to 800mhz, as this is what it claims to be capable of. I tried changing the timings from 5,5,5,15 to what the internet claims they should be at, 5,6,6,18. So i have tried various different options, ranging from completely out the box settings to what it should be once you have configured them, including some things in between.
IRQ NOT EQUAL, is the most common BSOD, though there have been one or two others, one didnt actually seem to specify what the issue was, it just restarted really quickly.

Hardware as follows:
inno3d 680i mobo
ocz 2gb 800mhz ddr2 (OCZ2VU8004GK)
q6600 go stepping
corsair hx 620

Does anyone have any ideas?
Thanks in advance