The power supply can be replaced. The iMac G4 uses a unique power supply that is actually two individual parts, yet they are attatched. You can buy them for about $30-$70 but it depends on your model, what is your screen size, and what is your processor speed? this can be found on the bottem of the access door on the bottem of the computer. Be careful when you lay it down, since I have worked on one of these once, and layed it down and the screen was cracked by a stray screwdriver bit on my desk, so make sure your careful (It made a nice "iHemisphere" though since I decided to just remove the screen assembly and arm.)