So I get home from work, start up Diablo 3, go take a wiz, as soon as I come back into the room I see my machine totally shut down while sitting at the Hero creation screen of Diablo 3 beta.
I try powering it back on and the thing starts up for a few seconds and then shuts down. Try it again, same thing. I give it a few minutes and take off the cases side panel, try it again, it stays on but no display on the monitor what so ever. No BIOS, nothing. All fans are spinning. Hardrives are starting.
I built this thing 2 years ago and have had very few minor problems, never hardware. It runs 24/7 just about.
I think I have narrowed it down to either the PS or the Mobo. On the Mobo, neither the Phase or Debug LED lights are lit up. The GPU's LEDs are lit up. The CPU heatsink and fan are spinning. I have dissassembled the whole thing, reseated everything, tried tot run it back on and exact same results. I have removed the GPU, and still do not get Debug LED or Phase LED lights on the mobo. No beeps, but I dont think this mobo has an onboard speaker. Heres the specs:
I forgot to mention, I removed the lithium battery to restart the BIOS as well as tried each RAM stick to eliminate them. Neither resolved the issue. Going to head to BB, its the cloest thing, to get a PSU as long as I can return it, just to test it out.
Your initial series of problems sound like the textbook symptoms of overheating. Although the follow-up is more puzzling. I agree the mobo and the PSU are the likely places to start. Possibly the PSU was what was overheating, or some underlying failure was causing it to behave that way.
Disconnect everything from your motherboard except CPU & heatsink, power supply, and system speaker. Connect the reset switch in place of the case power switch. Turn on the system with the reset switch. You should hear a beep pattern indicating a memory failure.
Silence indicates a problem with the PSU, motherboard, or CPU.