My computer either hard locks and i need to manaully reset or i get a BSOD. I get no errors in the event log most of the time. The only ones I have got say an infinite loop has occured in the graphics driver or that the graphics hardware is fualty. Ive tried multiple nvidia drivers so i dont think thats the problem and im pretty sure my graphics cards arent faulty. Computer specs: Gigabyte GA K8N Pro SLI mobo Athlon 64 4600+ X2 939 2Gb Corsair RAM 2x Geforce 7800GTX 256Mb Soundblaster X-Fi Enermax 600W PSU Things Ive tried... Reinstalled windows Reinstalled world of warcraft Tried multiple nvidia drivers Tried 2 BIOS revisions Tried updating wireless network drivers Tried removing wireless network card and using onboard wired lan Tried removing 1 video card Tried removing sound card Tried changing CPU to an old amd 3500+ single core Ran tests on the CPU and RAM Everything points towards the video cards being defective but i cant see both of the failing at the same time. I have never overclocked my system and it has always ran fine. Its not just WoW that the crashes happen in, i tried playing counter strike source and it does the same thing. Weird thing is, if i play against bots i can go for about 30 minutes without a lock up, but if i play online, it locks up within 2 minutes usually. I can run the computer for hours just watching movies and it will run perfectly. I ran 2 3dmark05s in a row and got 11500 which also suggests that my hardware is fine.