Good comments. I wouldn't have run it unattended, I was just hoping to debug the other problems. And yes it was my sole responsibility. Weird thing though the PS didn't have any warning sticker on it ... as I'd have expected it to.
But it's all a moot point now. Long story short: the next morning the fan worked briefly then died again, and that afternoon the PS gave up the ghost as well. So it's back to being a pile of spare parts again, unless/until I get hold of another PS. Useful parts though, 1G ram, 500GB drive almost new, and a DVD-RW (my first).
ADDED: Noone should try this at home.