PC keeps shutting down!

Okay so I am at a loss here.

My brothers PC keeps randomly restarting, like powers completely off then turns itself back on. It doesn't matter if he is playing a game or watching a video or even just sitting on the desktop. It also varies when it does it, like he will get a few hours gaming and then the next he just googled within the first 5 mins of a restart. We have tried various Troubleshooting methods including part replacement.

Things we have tried.
-Changed power supply
-Changed Motherboard
-Reseat RAM
-Taking out one ram stick at a time to see if we have a faulty one(Rebooted still)
-Switching PCI-lanes on GPU (more on that in a moment)
-changed CMOS batter
-Default BIOS settings(no XMP and any other settings to see if that was it)
-EXTENSIVE thermal monitoring
-Re pasted CPU
-Clean Install Windows
-Changed Outlets just incase
-COMPLETELY reassembled the Tower numerous times

Parts
GPU: GTX 1080
CPU: Intel 8700k
RAM: 4x8 Corsair Vengeance 3200mhz
MOBO: ROG Maximus CODE(old) and Some ASUS MOBO for Testing(Brand new bought, just cant think of the model)
AIO: Corsair 1150i (or something like that)
PSU: First one Corsair 750 Watt the new one we just bought is an EVGA 750 Watt
--Idk if im forgetting anything if so let me know

So on the ROG MOBO the POST code kept going between many different ones but kept landing on 7F which from my understanding is a video error but i do not see how that would randomly shut down the pc and then restart itself, maybe loss of video but I guess I could be wrong.

Idk maybe i am missing something Please HELP! also sorry if this is hard to read

Always my first question, how are the temps and airflow?

Do you have a spare gfx card to try or can you try the 1080 in another rig?

It might be possible that the actual wall outlet that you have your computer plugged into might have an actual electrical short in it.

I used to live in a house where the house itself had crappy power outlets and wouldn't even hold the plugs but when I did find an outlet that would hold onto it, I'd be good for a while then all of a sudden whatever device I'd be using, my pc or PS4, it would randomly restart due to a power in-flux.

It all changed when we called for an electrician to fix all the outlets and I no longer had a random restart.

NEW UPDATE!

We swapped GPU's and the 1080 in the other rig did just fine but the system we are working with still had the same issue with the new GPU in.

We verified the wall outlets were fine and just incase setup in my house just in case to rule out his house lol.

So now I am looking back at the CPU and kind of the RAM again, mostly cause He wants to avoid having to get a new CPU if possible.

It seems your done extensive troubleshooting and the only remaining constant is the CPU. This would make sense if your CPU is going bad. It may be some malfunctioning thermal protection.

If it is electrical spikes you may consider getting an uninterruptable power supply (battery backup) that is designed to allow you to save your work and shut down your pc in the event of a power failure but also does a great job of smoothing out electrical spikes. Some systems are more susceptible than others. This is a good thing to have anyway and will protect your PC in the future.

You could always apply new thermal paste and try it. A good paste will run you about $7.00 USD.

When I read 'random' I run SFC scannow - but if you go into the event viewer it may help narrow down the instability.

Based on the description of the problem most likely it is a thermal issue with the CPU.

Honestly if you have not cleaned out the AIO make sure that is done. I suspect it is. You might want to take it apart and check the fluid inside. It might have degraded and clumped up causing either it to plug or jam the pump or block the cpu block. I would proceed with that tear down next.

I know im late to the game but i had the same issue on my last computer. It turned out to be a bad power switch on the tower. I ended up unplugging it from the motherboard and using a pair of needle nose pliers to short out the pins if I needed to turn it on and off.

Heh, well, since this thread got bumped, did you ever get it sorted?

Random question: Are you using the cables that came with the respective PSUs? Not mix / match or third-party?

Quote:

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Originally Posted by AOD_Tymplar

Heh, well, since this thread got bumped, did you ever get it sorted?

Random question: Are you using the cables that came with the respective PSUs? Not mix / match or third-party?

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Tymplar is onto something. I've had extension cables attached between power supply to gpu/motherboard that were inferior quality and caused random crashes and reboots. Remove them if this is the case to retest. Otherwise, are you sure there is no hotspot on the CPU? I have an 8600 with a bad 4th core that would not hit 5gHz and cause crashes. Maybe try delidding and reassemble.