PC turning off at random times.. but all parts work under stress tests?

[flashheart85]

(not sure if i can post this here so sorry if i cant and delete it)

I'm working on a computer for somebody and it turns it self off (No errors etc). The pc can be on for 5mins or 5 hours before it turns off. I can be playing games, working on a spreadsheet or it can be just sat there idle when it happens. I have run multiple stress tests on the CPU, RAM, GPU, PSU etc and nothing ever shows up as wrong. It's as if somebody has just pulled the plug on a perfectly good pc (There are no slow downs before the crash etc)
Its currently running windows 10 (2 week old fresh install), i5 6700k (No overclock), 16gb of ram (DD4), 2070 Super GPU. 850W PSU, 2 hard drives (one ssd for o/s and one HHD)

(Only problems i can find)
The CPU (i5 6700k) reaches 48c under load... Which seems very low?
However, after running a three hour stress test it didn't crash and showed 0 Errors.

When checking events logs after a crash it simply says that
The system has rebooted without cleanly shutting down first. This error could be caused if the system stopped responding, crashed, or lost power unexpectedly.

any idea? I don't really have any hardware from that generation to swap in and out. I do have a PSU but it's currently being used in a different system and it would be a ******* to get out.

ANy ideas?!

 

[Tetras]

The CPU (i5 6700k) reaches 48c under load... Which seems very low?

It does, but an i5-6600K (there's no i5-6700K) doesn't have very high power consumption so a decent cooler could achieve that.

any idea? I don't really have any hardware from that generation to swap in and out. I do have a PSU but it's currently being used in a different system and it would be a ******* to get out.

When you're coming to a system that you don't know the history of that's a real pain! I don't really see what you can do, other than remove stuff.

You could take the graphics card out and use the onboard instead.

850W PSU, 2 hard drives (one ssd for o/s and one HHD)

What brand is it?

Its currently running windows 10 (2 week old fresh install)

Did it do this before the install?

 

[moppy89]

Sounds silly but is it mounted on standoffs properly? Not shorting out?

 

[theforce]

Is the motherboard using the latest BIOS version? Trying a different power supply would also help if one is available.

 

[Nathlm]

I know it sounds like I'm just pulling a solution out of thin air, but it really sounds like a PSU issue, but try starting with the easy stuff first, RAM, GPU etc. and then hopefully you can get the issue before having to swap the PSU

 

[TbirdX]

My money would be on PSU also. It doesn't sound like or exhibit the symptoms of a crash, more a sudden loss of power.

 

[ooStevo]

The standoffs is a good shout. Had that happen before. It means you'll have to dismantle the whole thing, but at least you can start from scratch,and hopefully isolate the issue along the way. Just a tip, don't install the motherboard back into the case whilst you are testing. Put it onto an anti static mat,then add things individually. Good luck.
Edit: I also agree the PSU is the likely culprit. What model is it?