Hi Guys, I have a G4 Dual 500MHz Sawtooth that wouldn't boot or show any signs of booting. I tried the battery in another machine, reset the PMU and various other procedures with no success. I then pulled out the PSU and and put in a old PSU from a working Beige G3 and I was shown some form of life. Now when I push the power button the optical drives flash on and there is a red LED next to the last stick of RAM labelled D55 illuminates and the fan cycles for about 5 seconds then stops. No activity on the monitor and the machine does not chime. Does this mean that the PSU was the original problem and the Beige PSU doesn't have enough power to boot the G4 or there still could be logic board problems? Thanks for all your help guys, I really appreciate it.