PC is randomly restarting due to power loss... PSU or MOBO?

[tomas_p]

Hi all,
so I build a PC 3 months ago, it was working just fine until yesterday when it restarted itself while I was playing Shadow of War. At first I thought my GPU overheated because its cooler is pretty small. When it booted up I opened CPUID to monitor temps, started game again but lowered the graphics a bit. After an hour gpu was at 81°C which is normal for that cooler at higher load. But today it happaned again, 30 minutes after boot up while on facebook, nothing else was open. After it booted up again I checked event viewer and it was caused by unexpected power loss, which means wrong PSU or MOBO or both. Also HWinfo shows one broken thermal sensor, but it is not visible in cpuid nor bios. Is there a way to find where that sensor is exactly on board so I can see if it is damaged (the value was changing between 89-96 °C)? Any ideas how to determine what is the exact cause of my problem are much appreciated.

I did find that bios update may or may not help but I do not want to risk that, if it loses power during update then the board will have to be repleaced for sure.
I also had mildly dusted intake filter on my PSU, however cleaning it did not solve the problem.

It happened again while I was typing this. But this time when PC started, all peripherals did not have power (all ports - USB/HDMI/DP/Jack). After hard reset ports were working again, which was a big relief.

Event viewer
HWinfo - CPU
HWinfo - mobo
CPUID - cpu, mobo

PC:
MOBO - asus prime z370-p
CPU - intel core i5 8600k (no overclock)
CPU cooler - Arctic Freezer Xtreme Rev.2
GPU - msi gtx 1080ti aero 11G
RAM - PATRIOT Viper LED 3000MHz, 2x8GB ,DDR4
PSU - EVGA 650 GQ

 

[R_1]

My canned random reboot Rant
Random reboots are usually caused by the PSU, the RAM or software AND in that order of likely-hood.
PSU - If you can borrow/swap a PSU for testing. sibling/friend you can swap out the PSU and each system will be testing the other.
RAM - run the system with one stick of RAM see if stability returns if not Test all the RAM with memtest 86 for three passes or overnight. if you get no 0 errors after more than three passes the ram is good. with the random reboots I would suggest running this test after the PSU swap or after the PSU has been cleared.
Software - Drivers or other issues can cause reboots. Boot to a linux distro on a USB drive. mint linux will boot to memtest86. you can run the OS from the USB and await reboot.
end canned rant