One of the reactions to my story of investigating a dead computer struck me as rather strange. Commenter Steve wrote, "Usually video cards left on a table don't works well (the one inside a computer have a better probability)."
While it's true that the ones inside a computer are more likely to work, it's not the case, at least around here, that the cards on a table are unlikely to work well. Many people have a small stash of cables and other spare parts specifically for repair purposes. If you see a video card on a table, odds are that it's part of somebody's spart parts stash and works just fine.
At least around here, we follow a different convention for indicating when things are broken beyond repair: We put them in the garbage can.
Joke-ruining clarification: Or the recycle bin, as appropriate.
Computer repair follow-up: Last Thursday morning, I turned on my home computer and it didn't boot. The symptoms were exactly the same as the previous death, so started with what worked last time: I unplugged the video card. The computer booted up.
It looks like my home computer eats video cards.
Now what? Do I feed it cheap video cards? Was this just a fluke and my replacement video card happened to be a dud? Are the video cards actually just fine, and it's the motherboard that can't cope with them? Do I abandon the computer and start over?
I'm going with option two: Assume I just got a bum video card and try again. But if the second replacement video card also dies within a short period of time, then I'm going to have to decide what I'm going to do with the computer that eats video cards.