I have a 1-year old homebuilt computer with an AMD 5600+ processor and EVGA nForce 590 motherboard. This is actually a rebadged Foxconn mobo. Up until now, it's been an excellent performer, probably the best I've ever had.

The other morning I came in and found the computer off. I thought that was strange since I never turn the computer off at night.

I rebooted, did some things, and 15-20 minutes later, the tower shut down all by itself. It would be like yanking the plug out of the wall, the tower turns off at the blink of an eye. No warning, no other symptoms.

My initial suspicion was a bad power supply. I swapped it out with another, but that is not the problem. The same symptoms are present with both power supplies.

Today I removed (disconnected) the video card, memory, hard drives, floppy and DVD drives, all USB devices, the network cable and re-tested everything. Nothing is different, the computer is still shutting itself down with only the CPU connected. Every time I've checked, the CPU temps have been 50 degrees C or lower.

What I've noticed is that whenever the motherboard is cold, you can boot and get 15-20 minutes out of it before it shuts down. If you reboot immediately, it lasts for maybe 5 minutes. Rebooting subsequent times, it doesn't even last long enough to load Windows.

I think it's a safe assumption that the motherboard is bad. Just my luck, I've only had the motherboard since 5-2-2007 and it has a 1-year warranty. Hopefully EVGA will be gracious enough to extend the warranty an extra 5 days.