Protools Legacy HEEELP!

[MrMuso]

Any help on this much apprecated..

I've had a stable systen running for the last six years with the following:

G4 quicksilver upgraded 766 (now running logitech dual 1.2ghz)
Protools Mixplug (Core + Farm)
Dual Ultrawide Glyph SCSI drives via ATTO card

After leaving the system shut for a few days I restarted only to find the power light come (immediately) on and off on the G4 and nowt else.

I tried everything (battery, PRAM, different processor) and took the machine into a specialist. We tried a different mac, but with all my cards. My G4 had certainly blown it's motherboard (despite power getting in), HOWEVER with the new cards in the new machine it still wasn't working!

Here's the crazy bit - the system booted up fine if just the two protools cards were in, or if the core card was in with the scsi card. However with all three it wouldn't!

I'm being told that it's a fault with the farm card (even though it boots with the two cards in).

Nothing quite adds up here - so you're aware we've tried a third G4 as well and it's still the same problem..

Any help / advise would be MUCH appreciated thanks!