I hope someone can help me: I have an Athlon XP 1800, my power supply died so I bought a new one (400 Watts), the computer ran for a day then wouldn't boot to the screen, had power supply checked and it was good. Suspected motherboard problem. Replaced the motherboard (ASUS A7V8X) I have DDR 266 memory. Now I can boot into the BIOS but as soon as the system tries to boot into Windows it shuts down (temp. looks fine), I changed Video to onboard video and same result, tried to boot from floppy but as soon as it goes to windows it shuts down. Runs o.k. in Dos until a program is run, I can't reinstall window because system shuts down. Does anyone know what is causing this? Could it be a bad processor?