I opened the PSU hopping to find a component obviously bad (so I could just replace it and move on), but there was nothing that I could detect as bad.
The exterior of the PSU was a lot more helpful, it clearly stated what the 8 pins were for:
Ground Ground Ground +5v
ON/OFF -12v +12v +5v
5v 4 A
12v 1 A
When I found this, I realized that this voltages and Amperages are within the range supplied by an AT PSU, and I happened to have one laying around.
My friend Google pointed my to this site
where they confirmed my suspicion.
So it was now time to do it.