I did the necessary conversions to the PC ATX as to match the pins of the Quicksilver, sans the ADC power lines. The machine still didn't boot.

I found out how this machine died, one of the students decided to have a bit of fun and flicked the red switch on the back, switched it to 110v and plugged it into a 240v line. I wouldn't be surprised if the logic board was damaged, although it could have suppressed it in the PSU if I was lucky.