This is new since yesterday, I don't know what's happening. My PC has been partially powering off suddenly and without warning. My displays lose input, my peripherals turn off, and the computer stops responding to everything. It's still "on" with fans spinning and the power button's LED is lit, but won't respond to holding down the power button to force it to shut off. The only thing I can do is turn it off at the power supply or unplug it.
I thought it was a one-time thing, but it happened again today. I've never seen this before. Anyone have any insight into what's happening?
Edit: I ran a memory test which came out clear. I ran stress tests on CPU & GPU, which didn't cause any issues. My temperatures have always been fine, with nothing ever going above 75 degrees. Eventually, the BIOS lost track of the date/time so that pretty much gave it away. The computer eventually stopped booting entirely, so I replaced the CMOS battery and everything seems to be running fine for now.
For the record, replacing the battery on an ITX build without taking the whole thing apart is somewhat of a pain.
If it's a desktop PC it may be that you need a new bios battery. Check the motherboard to see if it has a small battery on it and install a new one. See if that works.
What are your system specs and what is going on in task manager when this happens? Any processes using high cpu/ram? What does event viewer show if you filter by error/critical and events within the last 4 hours?
Any pattern to what precipitates this? Do you have another machine that to can use to remote into this one to see if the behavior occurs off your main monitor(s)?
Also, what is your OS drive available capacity? Is it over 90% full? Need a lot more info about what's being done on the machine and its specs in order to hazard an accurate guess...
This sounds almost the same issue I had. Have you tried to disable/uncheck “Turn on fast startup” from the system power settings? Another thing I did was open the troubleshooter, then click on Additional troubleshooters, then scroll down until you find Power and click on that.
One of those two helped fix my issue so now my computer shuts correctly.
If the memory is fine it would also be wise to check your hard drive, I had similar issues right before my old laptop drive failed. Also are you using an integrated graphics card or an external GPU? Some extra specs may be useful