Most common reason for this problem is an inadequate power supply. Try getting one that's at least 100W "bigger".
I built this computer about a year ago, and when I was putting everything together everything was fine. I decided to one of my video cards in at that time, because at that time it wasn't necessary to have both. A couple months ago, I bought the second card, and thats when it seems that my trouble began.
This problem happens pretty often. Its not like a certain program or a certain action, I will be listening to music, or playing a game or doing something then all of a sudden. Boom. The computer restarts, and I am back to square one. I've looked around the internet for anyone with problems like mine, and no one seems to have this kind.
Its not a good sign when you try to install the drivers from the cd given to you and you get a BSoD message.
I ran Memtest86+ and nothing came up, and I know my power supply is fine, but I don't know what my problem is.
I have an AMD Athlon 64 3700+
DFI Lanparty nF4 SLI-DR
1 GB of ram
2xGeForce 6800GS cards in SLI
Creative X-Fi sound card
I hope you guys can help me, I have faith. But if you can't does anybody wanna buy a 6800 GS?