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.