Computer sometimes shuts down and restarts under load

[shevtsod]

Hi!

I've been having some strange issues with my 1-year old computer that only started recently. Basically it completely shuts down (lights, fans, and everything) with no BSOD and immediately reboots, and this only appears to happen under load. I've had it happen while playing games and playing movies on a video player.
I'm not able to replicate it consistently, but I noticed that it crashed twice in a specific scenario - I opened up AC Origins and as soon as it hit the loading screen after the main menu (when the first 3D character models show up) it immediately shut down. This also doesn't happen consistently as I am usually able to get past the loading screen and play the game fine, so I wasn't able to replicate it this way, but I think it is suspect. Other times the PC would crash randomly after long play sessions in pretty undemanding games like Minecraft and Trine 2.

Here are some things I already tried after reading forum posts about similar issues:

• 
  ■ Uninstalled Nvidia drivers with DDU and reinstalled latest without GeForce experience
  ■ Disabled automatic restarts on failure, but system still restarts automatically after shutting down
  ■ Tried both a socket on my UPS and directly to the wall
  ■ I had some BSODs (not sure if related) with codes DPC_WATCHDOG_TIMEOUT and SYSTEM_SERVICE_EXCEPTION but I didn't have the correct Intel SATA drivers according to this and they seem to have stopped after I installed the drivers from my motherboard manufacturer's site.
  ■ Tried looking for BSOD dumps in C:/Windows/Minidump but it was empty.
  ■ Checked event viewer, no useful details except kernel power loss event
  ■ Checked PSU rail voltages, and they all seem close to nominal, no big drifts.
  ■ Ran memtest86 for an hour, no errors
  ■ Ran Prime95 for 15 minutes, no workers stopped, 90 degrees average on CPU (hot because it's the AVX version)
  ■ Ran Furmark for 15 minutes, no crashes, 65 degrees average on GPU
  ■ Ran OCCT PSU test for 5 minutes, no crash
  I haven't run the stress tests for long periods of times since I figured it would crash immediately if it was a power issue, but I can run them longer if needed.
  I'm suspicious of the unrelated BSODs I was getting as a sign of my Windows install going bad, so I would have tried reinstalling Windows next, but the shutdowns seem to be on a hardware level since there is no info about them in Windows. People often blamed the issue on a bad PSU in the forum threads I read, but those people all had old, off-brand, low wattage PSUs, so I'm not sure if that's it either.

My specs:

• 
  ■ CPU: Intel i7 8700K
  ■ GPU: Asus 1080 Ti OC
  ■ RAM: Corsair 2x8GB 3200 MHz
  ■ PSU: EVGA Supernova 850 G3
  ■ MB: Asus Z370-F
  ■ HDD: 2x Samsung 850 Evo 500 GB
  ■ No manual OC, but using XMP profile for RAM
  ■ About 65 degrees average on CPU and GPU in graphics intensive games, so no major heat issues

I'm kind of stumped at this point, any ideas?

Thanks!

 

[norcalsc]

I would go with a fresh install anyways, just to try and eliminate all possibilities, also set bios back to default. Try gaming and see if it's still happening, that way at least you know it's not either of those things. Power supply would be might first thought, you do have a quality unit. But that doesn't mean that there isn't something wrong with it. One by one try to figure it out good luck

 

[shevtsod]

True, that's a good way to go about it, thanks. I reinstalled Windows 10 on a spare HDD I had, reset my CMOS, and disconnected my other HDDs to isolate things as much as possible. I played for about an hour and a half and no shutdown yet, but I don't think thats enough testing to be certain. I'll test more tomorrow and see if it's stable, then test again with the XMP profile enabled.

 

[shevtsod]

Well, bad news, it did shut down again eventually.

I'm now running stock Windows 10, stock BIOS settings, and booting from a different HDD, but it shut down while starting up a game again. I was luckily recording HWMonitor with my phone right when it happened, so I managed to grab the exact frame before it shut down. I linked it below, and sorry for the crappy angle, hopefully the numbers are still legible.

https://i.imgur.com/n3Omb4j.png

None of the numbers look that off to me... They all actually look pretty low so it's surprising that it would shut down right then...

Does this really look like a PSU issue? It's still under warranty so I could RMA it easily enough, but I'm starting to wonder if something other than the power supply could cause this...

 

[shevtsod]

Yep, turns out it was the power supply after all. I got a hold of another PSU to test and everything's been working perfectly since, so I'll just have to replace my PSU now. Thanks for the help @norcalsc!

 

[norcalsc]

good deal!!!