It displays corrupt images after approximately 5 minutes from a cold boot, and almost immediately when running any 3D intensive application. These symptoms sometimes persist even after reboot, and extend so far as corrupting the text on the boot screens and BIOS menu. The machine is running twin Vega GeForce 9800gtx cards - the above symptoms occur both in SLI and non-SLI modes. The BIOS temperature monitor also shows the motherboard north bridge running very hot? (approx 83 degrees C). I can't work out if it is a graphics card, motherboard or cooling issue.