Gigabyte GA-P55-UD3L rev 1 Mobo, 8G (2x4G DIMM), Win10 (up from 7), 700w ePower EP700xp power supply. nVidia GTX-750 graphics using DVI to monitor.
My grandson was playing "America's Army" at near max settings on GTX-750. In the middle of the game, the computer shut down, hard!! Just blanked.
Tried to power up using on/off button. Button flashes on, then 3 seconds later goes out. There is no response via monitor. Hit the button again and it does the same thing. Pulled plug, waited, plugged in and tried again. No joy.
Pulled cover and put on thinking cap. Hit power button, fans at processor cooler and fan on GPU all start, then stop when LED goes out. Unit sits for 10 seconds, LED lights up, and fans spin. 3 seconds later, it all shuts down. Will cycle like this indefinitely. CMOS? Bought new CR2032 and replaced. Same results.
Just because I was brainstorming, I swapped memory modules, I swapped out the DVI video out for a VGA cable, I removed GTX750 and tried onboard vid, removed all USB connections except keyboard... I was tempted to unplug one of the 4 fans (2 case fans and 2 on liquid cooler radiator for CPU), but didn't.
Next step is trying another power supply. A friend will loan me a 600w unit later today. None of my spares can power SATA.
Am I on the right track? Would you troubleshoot differently? Anything I didn't cover?
Edited by PeaB4YouGo, 22 April 2017 - 12:25 PM.