Long ago my 9800 GT died, but while it was working I had frequent Bsods for some odd reason. Now that it died I'm using my Radeon HD 4850 but I still get frequent bsods. I tried Memtest64+ and I found something odd about it, when I tested each stick separately it didn't give any errors, only when I tried to test them both errors started to pop up. I also get random artefacts sometimes, tiny squares mostly wich then vanish. Currently I have two 2GBx1 DDR2 ram sticks, on a P5QC.