I have a "Mirrored Doors" aka "Wind Tunnel" dual 1 GHz G4 at home, a "second generation" dual 1.25 GHz G4 at work. I bought the Power Supply/Fan upgrade while it was offered. Curiously, my newer machine is the one that is REALLY noisy. My guess is that I couldn't use the upgrade kit on the second generation (early 2003) machine, but I thought someone here might have real information :) So, what say ye all? Jim Robertson --