From “the monitor goes dark”, it would be helpful to split monitor issues from computer issues. When the computer becomes unresponsive, do any “non-monitor” functions still work? Does the DVD-drive tray eject or does audio continue to play? Any other details? Do any other lights on the computer stay on, like keyboard and mouse lights?

If the issue is primarily the monitor, then splitting between the physical monitor and the video card would also be helpful.

How old is the hardware?

When you say “nothing is logged”, is the hard shutdown logged or anything after the time of the event? Or does “nothing is logged” mean the normal items are logged, but nothing of interest is logged? Some issues, especially hardware ones, stop the computer from logging.

Story: I once had a 15+ year old computer do something similar. The screen would go dark, but the lights on the keyboard stayed on. I had to hard power the system off and sometimes on boot the monitor wouldn’t work. A monitor swap didn’t fix the issue, but a USB video card did. The video card had failed. (Looking up what I think the interconnect was, the system may be 20 years old at this point.) NOTE: The system was not functional long term with a USB video card due to how the BIOS in the system handled the two video cards.

Not even a fucking made up sentence. That was a real developer expressing a real problem.