Hate to say this, but in my experience as an owner of about seven Powermac G5s, the issue is usually that the processor has become unseated or the powersupply blows or the liquid cooling thing happens.
The unseated processor has to do with the Chinese manufacturing process and yes an ungodly amount of thermal paste.
The powersupply is just a powersupply.
Overall, I have had GREAT luck with my G5s and All of them run perfectly at the moment. Even my single 1.8ghz from 2003.
The problem I have encountered is the lack of skilled diagnosticians.
Geniuses at the Apple Store are usually dumber than me.
Get an Apple Tech you can trust for your G5, someone who will really explain exactly what is going on with your machine.
They are great machines.
The OP needs to call Apple because his power supply is under extended warranty. My advice would be to take it to a real Apple Tech, not a Genius.
so having come back from the 5th ave store (my god apples making a lot of $$$) and having had a genius look at it, he said it might be the dust which, imo, there wasn't really too much of, and/or the logic board ($1,913) and/or the processors ($943). and $135 for the labour.
unfortunatley for me he can't tell me if its either/both unless i buy said item and have him install it.
I guess they don't have the means to test it unless customer uses US currency as a medium.
To his credit he took it in the back, vaccumed it out and upon replugging the power and.... nothing happened.
according to the tech standing next to him, it couldn't be the power supply bc it wouldn't turn on if that was the case.
also,
to the people that have the "let me drop the soap so you can get a better look" attitude;
i deal with some corrupt, greedy, crooked people within the music business. a large chunk of the foundation is based on an immoral, dont-give-a-f-unless-you-can-do-something-for-me attitude that is draining at best.
in order for you to get a somewhat fair share or your hard work, you've got to fight for it and make backdoors when there are none.
this in conjunction with my upbringing in nyc has taught me to fight what I think is wrong.
not trying to say i'm some tuff dude, but i'll be damned if i'm gonna let this go.
and yes, this does go above "complaining' about it in some internet forum.
california:
how does one go about reseating the processors?