I was called to a friends' place last week because their puter stopped working. I did the swapping dance and determined that their PS was dead and the motherboard too.
The mobo was a ESC Via chipset with a 2600+ on it. OK. No biggie-the cheapazz (e-machine) PS killed the mobo. That I've seen.
Funny thing is I rebuilt their computer this afternoon (thanks Newegg), fixed up the software/drivers, removed spyware and tidied things up, and delivered it to find their keyboard was dead too.
So I figure:
PS death knell kills the motherboard and keyboard connected to it, or...
Keyboard short kills the motherboard and PS overheats.
(both would be new ones to me, after >10 years as a hobbiest, then pro, then hobbiest technician.)