My computer is a self-build, and here's what it has:
Motherboard: ASRock Z170 Extreme4
CPU: Intel Core i7
Memory: GSkill RipJaws V DDR4 2x4G
Power: EVGA NEX650G 650W
Video card: EVGA GEforce GTX 1060
The other morning, after a night of heavy rain, but no thunder that we heard, my computer was off and would not turn on again. I immediately suspected the PSU, although some of the case LEDs and the lights on my mouse were on. I tested the power cord first (on another computer) and it worked fine. I noticed that when I unplugged, replugged and turned the PSU in my computer back on and pressed the MB's start button, the PSU fan would come on and spin for a second, then stop, and no matter how I pressed the MB power button, it would not come on again until I repeated the process.
I went through the steps in this video:
All connectors are well-seated. I tested the power-to-case power button and it made no difference. Once again, the first time trying the PSU fan spun for a sec then stopped.
Then I jumped the power supply (after disconnecting the CPU power cable, SATA power cable, and graphics card power cable). When I did this, the PSU's fan came on and stayed on. I tried turning on the case's LEDs, but I don't think they came on. As suggested by the iBUYPOWER guy, I then plugged each of the power cables back in (still having the MB power cable in jump mode.) The PSU fan would spin up each time (I turned it off and back on between cables.) However, when I plugged the MB power cable back in, the PSU went back to its previous behavior: fan spins a moment, then stops.
All of this leads me to fear I may need a new MB. Some other things I noticed:
CPU cooler & fan was full of gunk (I blew it out -- very dusty -- I'm so embarrassed.)
I saw no blown capacitors.
Tried clearing CMOS (the MB has some handy buttons for doing this) -- no difference.
There is nothing obviously wrong.
So I'm hoping to find out if there's something obvious I'm missing (or something else to check,) how to determine if it's the MB's fault and it needs replacing, and/or any other handy suggestions anyone has. If I must take it completely apart, I will.