PC Aggressively Shuts Down And Now Doesn't Boot Up.

CrypticGreyCynic

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Jun 11, 2017
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One evening I'm on my PC that has been working for 6 months flipping through tabs in chrome and randomly the PC aggressively shuts down. I spend the next few hours powering down and up, plugging and unplugging the power cable, changing wall outlets, etc. Finally I leave the PC unplugged to go take a shower, I come back, plug in the power cable, and the PC powers on as normal. I'm checking things and everything seems to be normal. Restarting the PC didn't have any affect, but when I completely shutdown the PC it wouldn't ever boot up again. The only things that the PC will do is: the graphics card's LED's and fans turn on, all the case fans turn on, the NZXT Kraken X61 fans turn on, the LED's on my Corsair RAM turn on, the red CPU LED is on, the power and reset LED's are on, and the Q-code 00 is displayed. I've completely dissembled the PC and trying to diagnose the problem to no avail. Flashed the BIOS with the latest BIOS update and that didn't fix the problem. Tried running the PC with nothing but the AIO water cooler, PSU, and CPU with no success. Took out the CPU, examined the motherboard CPU socket to find any bent pins and there weren't any, put the CPU back in, put the AIO water cooler back on and still no success. I do not have any spare "known good" parts to try. I'll list my specs below if that helps. Thank you

Update: Couple weeks later the PC is now booting up as normal, but it will shut down immediately at random times while I try to use it. I managed to run the ASUS PC Diagnostics utility before the PC would shutdown and memory under stress test says internal error.

Update #2: The PC does not shutdown randomly anymore. I ran MemTest86 V7.3 and there were no errors. I also ran Prime95 for 24 hours straight with the CPU at 100% load and the RAM at 90% load. Prime95 never caused the PC to shutdown and didn't show any errors.

OS: Windows 10 Education 64-bit
CPU: Intel Core i7-6800K Broadwell-E
Mobo: ASUS X99-A II
Graphics Card: EVGA GeForce GTX 1070 FTW
PSU: EVGA SuperNOVA 850 P2
RAM: CORSAIR Vengeance LED 32GB (4 x 8GB) 3000MHz
SSD: SAMSUNG 850 EVO 500GB
HDD: WD Black 2TB 7200 RPM
PC Case: Fractal Design Define S
AIO Water Cooler: NZXT Kraken X61
 
Solution
I'm more inclined to think its a PSU fault, even high end ones can develop a fault. Your description of leaving and then being able to boot is typical of a psu fault where the capacitors have to fully discharge before the PSU can reset. Only way to test this is by trying a known working PSU.

harrysmellington

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Jun 23, 2016
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Did you try 1 RAM stick in differing slots for the memtest? It sounds like maybe a power supply or thermal sensor issue or more likely a bad ram stick. I assume when you say " aggressively shuts down " you mean it cuts out with no blue screen. This could mean some protection system is being tripped or something is causing total failure of the system (bad RAM card for example).
 

CrypticGreyCynic

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Jun 11, 2017
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I ran memtest all night a few months ago with all four RAM sticks and there were no errors. That is the only time I have used memtest. I rearranged the RAM sticks in many different configurations and that didn't change anything. Yes, when I say aggressively shuts down, I mean that the computer shuts down instantaneously with no blue screen. So a bad RAM stick or multiple bad RAM sticks can cause a computer to abruptly shutdown with no blue screen or reboot? Why would the computer's red CPU LED be on, the Q-code 00 is displayed, and after a couple whole weeks, works as normal with random shutdowns that don't cause the computer to show the red CPU LED and Q-code 00 like before?
 
I'm more inclined to think its a PSU fault, even high end ones can develop a fault. Your description of leaving and then being able to boot is typical of a psu fault where the capacitors have to fully discharge before the PSU can reset. Only way to test this is by trying a known working PSU.
 
Solution