Broken Computer Curiosity

[BrianG]

One of my computers at home has been down for a while now, but it was the kids' computer, so I wasn't too much in a hurry to work on it. Initially, it would sort-of boot up. Sometimes it would make it past the BIOS, sometimes it would get to the Windows loading screen. But at some point, the video would get scrambled and stop booting. I had tried a new vid card, HDD, etc. I removed all non-essential items (add-in cards, CD, floppy, etc). Nothing seemed to help so I shelved it for a while.

Well, I decided to take a look at why it wasn't working last night. When I took everything apart, I found that all the 5v slots on the main mobo connector were melted and blackened! All the rails on the PS (Antec TruePower 450) still work fine, even under load. There are no discolored areas on the mobo, no bulging caps, no discolored CPU/memory/AGP/PCI connectors, and all ICs look fine visually. There was no loose metal parts floating around inside the case either.

I'm kinda stumped. It seems as though nothing was wrong. The only thing I can think of is maybe the contacts for the 5v line were not perfectly connected and overheated from the current draw.

The mobo connector is pretty much toast, and it's an old GigaByte GA-7VRXP, so it's not really worth fixing, but I'm curious what happened. The highest current draw on the mobo would be from the 12v line (uses switching regulator to power CPU core), but can't think of what would use the 5v line so heavily?

Don't know if I want to replace the PS connector, or convert the PS to another 12v PS for charger duty.