Specs and troubleshooting steps are listed below.
I'm having a weird new problem with my PC. The computer was built a few years back and has been running without issue. About a week ago, I left my computer on for a few minutes while I went to the kitchen, and when I came back, the display was black and wouldn't get a signal from the computer. I tried restarting it, however, it still didn't display anything. After unplugging the PSU and restarting, the computer started working again. This time, the screen was flickering as if the graphics card was failing, with lines appearing and disappearing horizontally across the monitor. I'll list out the symptoms here:
The computer will power on, but the screen flickers like described above. After a few minutes, the computer will suddenly restart with no warning.
The computer will not power on. Instead, it will display show the VGA light on the diagnosis LED's, which will disappear after about a minute. At this point, the peripherals light up and the fans start spinning faster
The motherboard will not display any diagnostic lights, but all the components will spin up, but the screen stays black.
Here are the diagnostic steps I have taken:
Completely disassemble and reassemble the computer (no impact)
Purchase a new power supply (did not resolve the issue so I returned the PSU
Purchase a new motherboard (did not resolve the issue but I have retained the old motherboard for now)
Reset the BIOS on both motherboards, which sometimes makes the computer boot up but then it will crash again.
Disconnect the power supply from all the components and then reconnect it, which usually resolves the VGA light issue but then the PC crashes again shortly after.
Try powering on with no peripherals connected other than the monitor (no impact)
Here's where it gets a little bit interesting. I tried starting up the computer outside of the case, and it ran flawlessly for an hour or so without any hiccups. When I put it back in the case, it started crashing again, so I thought that maybe something was causing a short and making the PC crash. I took it out again and left it running outside of the case for 2 days. I then cleaned the case and removed any other debris inside the case. I put the computer back in, and it was still crashing. However, now, it is not powering up again outside the case either, which means it's probably not the case that's causing the issue.
I'm completely stumped at this point and don't have any ideas so I was hoping you guys might have some suggestions on what to try.
The specs of the computer are:
AMD Ryzen 7 3700X
MSI B450 Mortar Max (when the issue started), currently running MSI B550M PRO VDH WIFI
ASRock Radeon RX6800 16GB
16GB Corsair Vengeance Pro RGB
Corsair RM750 PSU (have tried a Corsair RM750e as well)
Samsung 980PRO M.2 NVMe
Fractal Meshify 2