Went to use the desktop yesterday (Advent 3516 - MSI Mobo P4 3.06Ghz), and it got past the initial BIOS screen, then came up with an exception and just locked up.
Wouldn't power back of with the button, So I had to unplug it to turn it off. Tried a couple more times, but just the same.
So took cover off, had a bit poke around for any loose wires/connections, unplugged stuff, but still the same.
Eventually checked to see what the PSU was doing, and it was putting out 7v on what should be the 5V standby wire, but I thought it was the volt sense at the time, so just ignored it (I only dug out the ATX wiring diagram this morning).
Left it at that and went to work (was on back shift).
Came home, and was just about asleep when the computer powered up by it's own. So just pulled the plug out and ignored it til today.
Purple wire was only putting out 0.25v, so had a search through the old PSU collection, but couldn't find a good one with the extra 4pin 12 connector, so robbed the PSU out the old Packard Bell in the workshop.
Plugged it in, but the mobo only powered up for a couple of seconds before shutting back down. Had a look at the PSU, and noticed it didn't have a -5V wire, so found a known good old style PSU, and bodged a 4pin connector on to it, but the computer still only powers up for a couple of seconds.
It's as though the power button is jammed on, but it tested ok.
Anything else I could try, or would I be right in guessing the mobo is toast?
Graphics card is ok, as I've swapped it to the PB to get a reasonable working desktop. I'll probably try swapping the gigabit network card later to get the network storage back upto speed.
