After fiddling with a new video card and seeing the computer was running, I moved it back under the desk.
Then it wouldn’t boot up.
“No problem.” I thought, considering that I was going to upgrade anyway. Then I remembered that parts of the novel are currently saved on its hard drive. Not really an issue since I can get to that data by putting the hard drive in an enclosure or swapping it into another system.
More of an annoyance than anything else.
I’m going to take a wild stab that it’s a power supply issue, and replace that first.