Desktop power issues. If I leave in BIOS (to check temperature) - will stay running - left it overnight. If I let it boot to anything- MEMTEST or Windows, it turns off within a few minutes. I have checked cooling, replaced power supply, 1 pass of memtest on 1 stick - can't get it to stay on long enough to do both or mulitple passes. Motherboard is Asus M3a78-T. Running out of things to try.