I have a G4 Quicksilver dual 1 GHz. It will power on, fans turn, HDD spins up, but no video, and the LED only comes on when you press the power button, it then turns off on both the tower and the LCD studio display. Any thoughts? I have reset the PRAM, pulled the battery and replaced it, swapped out the video card, tried a different HD. None of these has worked. I am using a cable for the HD that i'm not sure of its origin, but even with that disconnected I still have the same symptoms. Help!