PC is randomly shutting itself down, and several hours later starting itself again?

[robulon]

I built my PC in October 2021 (only parts kept from my previous build were my hard drives and the case). Since building it, it almost daily will randomly start a windows shut down on its own, seemingly completely unprovoked. Once it turns off it will stay turned off, i.e. it won't restart itself immediately. The shut downs have occurred in the middle of gaming, as well as in the middle of light browser use with only chrome open on my PC with a few tabs.

Alongside this issue, it also turns itself on seemingly randomly as well, typically several hours after it has been turned off. It does this after it is turned off by me normally, as well as after times when it randomly shuts itself down. The turning on of itself is always seemingly randomly timed.

Yesterday for the first time, it did the same random shutdown, after which I immediately turned the PC back on, it then shut down again after about a minute, then when I tried to turn it back on it got stuck in a loop of starting to power up for 1-2 seconds, then powering off then starting again up 1-2 seconds, over and over, no longer even getting through a full start up. After turning it off for 15 minutes it turned on properly and ran until I chose to turn it off.

This is my PC:
CPU: AMD Ryzen 5 5600X Processor
CPU Cooler: Cooler Master Hyper 212 Black Edition
Motherboard: MSI B550-A PRO Motherboard
Memory: Corsair Vengeance LPX 16 GB (2 x 8 GB) DDR4-3200 Memory
Storage: 931GB Crucial CT1000MX500SSD1 (OS)
Storage: 476GB Crucial CT512MX100SSD1
Storage: 1863GB Western Digital Blue HDD WD20EZAZ
Storage: 1863GB Western Digital Blue HDD WD20EZAZ
Storage: 931GB Western Digital Blue HDD WD10EZEX
Video Card: Zotac GeForce RTX 3060Ti Twin Edge LHR 8GB
Case: Fractal Design Define R4 PC Case
Power Supply: Corsair RM750x 80 PLUS Gold, 750 W Fully Modular ATX Power Supply

BIOS version: E7C56AMS.A50
AMD chipset revision number: 3.10.08.506
OS: Windows 10 Pro
OS build: 19042.1466

For some context, my previous PC build near the end of its life started crashing randomly, not shutting itself down as I'm experiencing now, but just sudden total power off as if I had held down the power button on the top of the case. This was actually the main drive to rebuild (it needed it tbh, it was an old build). So its frustrating to now be facing a similar problem.

I can't tell if its the same issue resurfacing, or a coincidentally similar problem, albeit not identical.

I have been going to all sorts of forum posts to try typical fixes for both the random shutdowns problem and the random startups problem, without any luck. I have tried the following:
- Disabled Fast Startup
- Disabled keyboard/mouse/network adapters from being able to wake my PC
- Disabled automatic restart if there is a system failure
- Ran Power Troubleshooter - this did pickup that I had my sleep & hibernate timers set to never, which it set back to some normal times. I tried to see if it was this, but the problems still persist.
- Replaced the stock AMD CPU cooler with a new Cooler Master Hyper 212 black edition, in case it was a CPU overheating issue. This has not solved the problems, but it has reduced my CPU temps.
- Ran the SFC through command prompt. This did find issues which it repaired, however the problems still persist after these were apparently fixed.
- Updated the AMD chipset driver

I have yet to try updating the BIOS, as I am worried about bricking my motherboard as I have no way of knowing when the PC might shut itself down.

Considering what I've tested already, I think it may be something wrong with my OS? Doing a clean install of Windows 10 is an option, however I'm hesitant to jump to that before getting advice on what else it could be.

What could be the cause of the random shutting down, and of the random starting up? Are they both part of the same issue? How can I solve these to get my PC running smoothly and without these regular problems arising?

Thanks

 

[weekendgeek]

Possible faulty case power switch or wiring from the switch to the motherboard.

You could change the windows setting for what the power switch does. By default it's set to 'shut down my PC'. Change it to 'Do Nothing'.

That won't stop it from starting up by itself.

You could also disconnect the switch from the motherboard and move the reset switch to the power switch pins and use that instead.

 

[robulon]

Possible faulty case power switch or wiring from the switch to the motherboard.

You could change the windows setting for what the power switch does. By default it's set to 'shut down my PC'. Change it to 'Do Nothing'.

That won't stop it from starting up by itself.

You could also disconnect the switch from the motherboard and move the reset switch to the power switch pins and use that instead.

Thanks, I'll give this a go and see how I get on, makes sense that it could be the case's wiring to the power button, I've been using the same case since Jan 2014.

 

[Caring1]

Why so many drives?
Disconnect all but the boot drive and test.
It may also be related to the LPX Ram.

 

[weekendgeek]

Why so many drives?
Disconnect all but the boot drive and test.
It may also be related to the LPX Ram.

OP stated it's doing a Windows shutdown, not crashing. It's also turning itself on - both behaviors that mimic pressing the power button

 

[Caring1]

Check the event logs to see if anything shows up that may trigger a shutdown and restart.

 

[maxfly]

Possible faulty case power switch or wiring from the switch to the motherboard.

You could change the windows setting for what the power switch does. By default it's set to 'shut down my PC'. Change it to 'Do Nothing'.

That won't stop it from starting up by itself.

You could also disconnect the switch from the motherboard and move the reset switch to the power switch pins and use that instead.

Yep, all good advice.
There's a short somewhere between the mb and power switch or the power button itself is damaged, getting stuck or just worn out. Or possibly the inserts that go over the mb pins are broken or loose.

 

[Ferd]

Maybe a driver or drivers are causing this issue.

to rule out hardware issues I would do a fresh windows install on a spare drive .

 

[robulon]

Possible faulty case power switch or wiring from the switch to the motherboard.

You could change the windows setting for what the power switch does. By default it's set to 'shut down my PC'. Change it to 'Do Nothing'.

That won't stop it from starting up by itself.

You could also disconnect the switch from the motherboard and move the reset switch to the power switch pins and use that instead.

This seems to have been the fix for my issue! Haven't had a single random shutdown or startup since disconnecting my power switch from the motherboard and replacing it with the reset switch.

Thanks so much for the suggestion