As I wrote in another thread, I somehow don't buy the planned failure rate on the G5's.
Mine run perfect and quiet and wonderfully.
Dust that holds in heat may be an issue that also can affect the logic boards.
This is the other issue I am guessing besides the G5's that have liquid cooling but I'm somehow guessing it is a dust issue at the heart of it.
I could be dumb and sentimental but when these babies work they work.
Mentioned on another thread that a friend's G4 500mhz tower from 1999 was his main computer until a month ago when he put in a 1.8ghz Sonnet upgrade.
That thing has more years in it yet.
The G5s also have that power issue because they suck so much juice -- make sure your G5s are on surge protectors...