I've had this problem a few times- almost every case was RAM that wasn't properly seated. Twice turned out to be bad RAM. Start with the easy- unplug all unnecessary stuff, opticals, HDD, extra cards, etc. Reseat the RAM, use one stick and if it stil BSOD, use the other. If one works, try the other by itself. If they both work, then try both at the same time. Try different slots also.