Just to let you know, my Mac is now up and running fine. A word of warning though for anyone attempting to use a thermal paste as opposed to the thermal pads which were originally fitted. Trial fit the heatsink onto the logic board first. On my G4 there was a small visible gap between graphic chip and the heatsink, the gap is easily taken up by the thermal pad but if you used a thermal paste only I don't think it would bridge it, or you would have to use a lot of paste which is not how its supposed to work. Just my experience.