Computer killing itself at random, and I don't have a clue why.

I think this is hardware due to the bugcheck that I remember. I'm really scared it's the GPU but typically that doesn't kill computers in this fashion...typically. Although, I did once have a laptop GPU that when it died didn't produce artefacting and instead the screen would just freeze and the whole computer would lock up... that said,

Hardware:
Ryzen 7 5800X3D (purchased used in Nov 2024)
ASRock B550M Steel Legend
G.Skill Trident Z Royal 32GB DDR4 3600
Mushkin PILOT 500 GB M.2-2280 PCIe 3.0 X4 NVME SSD
SK Hynix Gold 1 TB 2.5" SATA SSD
Crucial MX500 2 TB 2.5" SATA SSD
Intel Wi-Fi 6 AX200 m.2 adapter
Yeston Sakura RTX 4070 12GB
Elgato HD60 Pro

Peripherals:
Two Acer EB243YU monitors over DisplayPort
OMO100 Keyboard in 2.4Ghz mode
Logitech G703 in wireless mode
SteelSeries Arctis Pro Wireless

OS: Initially was using Windows 10 22H2. Continued to occur after a fresh Windows 11 install.

Timeline:

Sunday 8/9: I was playing a Nintendo Switch game through the capture card when suddenly, the screen froze and a BSOD appeared on my left monitor. I thought that's weird, but didn't really take note of it since I thought I could look at the details in Event Viewer once the computer rebooted. Once the computer rebooted however, there was no bugcheck event found. There was an error that said a crash dump was unable to be saved. The computer continued to work without issue the rest of the evening.

Monday 8/10: No issues. Played Helldivers with friends.

Tuesday 8/11: I turned on the computer and went to update Genshin Impact, then left the room. A few minutes later I come back and the left screen is a BSOD again. I remember this one was WHEA_UNCORRECTABLE_ERROR. After reboot, it loaded to BIOS settings. I turned off XMP, saved, and exited.

Windows began Automatic Startup Repair. It booted to the login screen. However, when I logged in, it started "Preparing Windows..." and then loaded to a generic desktop with a message: "We can't sign into your account" so I went to reboot. The Start Button did not respond and another message appeared: "Critical Error - Your Start menu isn't working. We'll try to fix it the next time you sign on."

I used Ctrl+Alt+Del to pull up Task Manager, opened a Command Prompt, and rebooted using shutdown /r. Upon reboot, the same issues reoccurred. So, I then used Command Prompt to boot into Safe Mode with Networking. Safe Mode also couldn't log into my account, nor was the taskbar responding there.

In Safe Mode, I ran SFC /scannow and it found errors, and directed me to use dism to correct them. After figuring out the syntax, I started dism but it could not find a source to repair from. I found my original Windows 10 bootable USB and tried to use that as a source, but dism still failed (perhaps because it was an outdated build?). I opened Event Viewer and found tons of bad block errors starting from the second BSOD. No bugcheck, not even a no crash dump error this time. In fact, anything prior to starting up in Safe Mode for 8/11 was missing.

I ran a CHKDSK and it prompted to reboot to complete repair. Before rebooting, I opened CrystalDiskInfo and it says my drives are all Healthy (though the volumes aren't, I guess). I was able to copy my user folder to one of my SATA drives so thankfully didn't lose any data. Then, I rebooted.

It ran through the same repair steps as before, and still couldn't sign in to the account/use Start Menu. Rebooted back to Safe Mode. I thought, "Well, I was going to upgrade to Windows 11 anyway, so I might as well make a bootable drive." Except, the bootable media creator program would run into an error and could not create media.

I booted into the Windows 10 USB and tried dism again from the USB, no luck. Decided to wipe and fresh install Windows 10 to create the Windows 11 USB. This seemed to work - I was able to install Windows 10 and run the bootable media creation program without errors on a different USB stick.

Wiped the drive and fresh installed Windows 11. It seemed to be running fine, so I started updates and let the computer continue updating overnight.

Wednesday 8/12: The computer was sleeping due to idling after completing updates, so I woke it up and tried to log in. The spinning loading wheel suddenly froze, and then the screen went black and came back with the error CRITICAL_PROCESS_STOPPED, tried to repair, went black again, and then came up to a old Windows Boot Manager with the error Windows failed to start, some options, and Info: The selected entry could not be loaded because the file is missing or corrupt. I inserted the Windows 11 USB, but neither Enter = Continue nor ESC = Exit seemed to do anything. I hard rebooted the computer and it loaded into BIOS.

I decided to completely disable PBO (which had previously been set to auto aside from a throttle temperature). I checked the boot order and only the USB bootable drive showed up there, so I saved and exited. To my surprise, I had mixed up the two drives (they are the same model, different color) and it was actually the Windows 10 drive. I exited and rebooted again.

Now...because I have been suspicious of the GPU up to this point, I swapped the DisplayPort cable of the left (second) monitor to a different port on the GPU. I should explain why I was suspicious. That is recently, the second monitor seemed to have difficulty recognizing the signal automatically and I would have to wake it up to get it to show the desktop. I also have had frame drops in games that should not be dropping frames, but that could be unrelated...?

Well, the computer was able to log in this time. No errors. Seems to be running fine. Stressing the GPU with Furmark didn't do anything. I ran CPU and Memory tests in OCCT but they came back 100% clean. So I went back into BIOS and re-enabled PBO and XMP, then ran the tests again. Tests still came back clean.

It worked the rest of the evening, but I can't say I trust it. Could it really be the port on the GPU went bad and was throwing the rest of the PC out of wack? Or is it something else and diagnostics are lying to me?

I really don't know where to go with troubleshooting from here.