OK... have a G4 Quicksilver 2002 820-1342 mobo with 933 processor (133 Mhz bus).

I bought a second-hand 661-2591 Dual 1Ghz processor module, after being assured it would work.

I fitted it... it didn't boot.. I re-fitted the 933 module... it doesn't boot. White button lights up when the machine is powered up, then goes dark.

Questions:
1. Is the 1Ghz module NOT compatible then, and have I fried my system?

2. Could it be the PSU?

3. Any other ideas?

Blimey... one dead mac :((((