Dual Processor not Dualling

Hi,
I’ve got a Dual P3-1ghz pc that we use for rendering animation frames. Its got WinNT4 installed, and 1gb ram.

When booting up with both processors i dont get a gfx display, there is no POST beeps, and i think it doesnt do anything.

When booting up with a single processor i can see all..e.g. bios info, and then it goes into windows.

i’ve tried changing the processors, different slots, re-jiggin memory. I even thought it was the mains power supply, so swapped it to the other side of the office. Still no joy 🙁
I dont think its the PSU either, as i’ve swapped that out with another one.

Any ideas gang?