Original post by: Brian Anderson ,
I have seen many G5 iMacs fail due to both PSU issues as well as capacitor problems. There are two types of caps on the logic board and (like most caps) when they die, they bulge and leak electrolyte. Before checking the PSU, make sure that all of the capacitors look good. They /are/ replaceable if they're bad and you're handy with a soldering iron.