PC Master Race

That seems like a normal restart initiated by using the start menu. The error code 0x80000000 does stand out, since on my personal Windows 10 install a normal restart gives a code of 0x0 (Indicating success). The "Other reason (Planned)" is normal though, it's simply the default reason for the shutdown command. The error code 0x80000000 isn't actually a specific error code that says anything, it's basically the 'empty' error code (Since error codes from windows system calls range from 0x80000000–0xFFFFFFFF). I think it might simply mean the restart was cancelled, which you would know if you did, or maybe if the restart failed for an unknown reason.

Did you confirm the message occurred roughly around the time the unexpected restart occurs? If the timing doesn't align, it might just be a complete red herring.

But if it aligns, something is somehow using your file explorer or task bar (which is what explorer.exe is) to initiate the restart, which would be unexpected since most often it would just directly shut down the computer by issuing the command for a restart directly (And you would see the process that initiated it instead of explorer.exe)

You might be looking at something that injects itself into the windows explorer, or something that directly uses keystrokes or mouse inputs to control the start menu (But you might be able to see that if so). Not necessarily nefarious but you should be on guard anyways. Maybe hotkey or macro software, or software you installed that works through the right click menu in the file explorer, or anything that adds itself on top of the default windows explorer like toolbars or plugins. A virus or such would be possible too, although one would wonder why it would just restart the PC and not actually do anything in secret. In cases where it's not a virus, there would likely be a pattern to where you perform a specific action and the restart occurs.

I would probably run down a classic troubleshooting checklist like remembering if you installed anything recently that aligns with the issue starting to occur, checking if there's any unknown applications starting with windows (You can check this in your Task Manager -> Startup), and running antivirus more aggressively (Such as scanning the entire disk). And if you can, ask around on forums where people much more familiar with this stuff hang out (Like here) or involve someone with more knowledge that can physically access the PC like a local computer repair shop or a tech-savvy friend.

Stress test your GPU and see if it crashes.

Then use somethibg line LACT to limit GPU wattage draw and see if that prevents crashing. Prime example of bad PSU if so

That's a fair comment, but there's a secondary reason I suggested it, eliminating the OS as a potential cause. If it still crashes while booted into memtest86, it's much more likely to be a hardware fault, on the other hand, if it stays running overnight, it's more likely to be software.

I believe the default behavior is to crash dump and restart on BSOD. Holding on BSOD display must be configured.

If there are absolutely no errors in event log before the restart, PSU really is a top contender. The system will have had no warnings of any kind. If the PSU stops delivering adequate power, it's likely to restart, and this is at a low level (i.e. the motherboard restarts the system).

It's difficult to diagnose too. For mine, I was able to get more-or-less consistent restarts by requiring more PSU current by putting the system under heavier load. Once I saw the restarts occur as fans / drives / GPU were spooling up, I swapped my PSU. That was the issue.

The good news is that (well-made) PSUs usually fail in a way that won't damage components. And yes, even good PSUs can fail, especially if they're being used above their rating. And even the best PSUs don't last forever -- best practice to change them out every few years, in any event.

Maybe faulty ram? Pull out all ram sticks but one and see if it happens again if it does swap ram sticks until it doesn't.

If that doesn't solve it it may be a failing PSU or other major component like the GPU or HDD.

A good starting point is removing everything not needed to boot and slowly adding them back again until it fails.

I'd throw memtest on a throwaway usb stick and let it run tests overnight or so, unless errors appear immediately.

Easier than doing a reinstall. :)

Ah there goes my idea, I thought it was gonna be down to Microsoft's inability to not fuck sleep up every couple of years

Memory is probably the next port of call if you don't see anything in event viewer to indicate a driver issue.

Another commenter suggested memtest which is a good shout, might be also worth putting a Linux distro onto a flash drive or partition and try running that for a couple of days to see if it does it under Linux, that will at least help inform you as to whether it's hardware or software

Got it, my first guess was Windows Update, but that definitely isn't the case. When you say restart, did you actually see the whole shutdown and startup process, or did you just come home to find it on the login screen with nothing running? Also, have you checked the Event Viewer to see if anything was recorded there?

Thought it was a double post because it showed up twice on my feed within seconds of each other, and I didn't notice different communities, sorry.

Windows 10

Yea that’s your problem.

And I’m not trying to be a “hurt durr use Linux” but my wife’s windows laptop will do that from time to time and none of my Linux PCs does anything other than what they’re told.

It's worth trying before replacing a PSU or memory.