I had one 2Ghz G5 iMac die on me. The symptom was a slow degradation of performance followed by some crashes, then some kernel panics, then refusal to start at all. I ran the hardware utility on my startup disk and even that crashed.

There is a problem with the power supply being "too hot". The heat essentially "cooks" a grouping of capacitors above the power supply.

Visually, one can determine whether their power supply is too hot by opening up the back and looking for a ghosting near the power supply. This is an indication of excessive heat. Looks like a watermark or smudge on the case exterior.

Also, if your iMac dies, you can look at the grouping of capacitors (look like little cans in a group). Notice the tops of the capacitors in this grouping compared with capacitors elsewhere. The tops of the capacitors near the power supply seem to have the tops bowed out (as if the were cooking and expanding under pressure.

Although Apple was happy to correct the problem, I would suggest getting Apple Care for every iMac. Its a great machine, but complex and has expensive parts to repair. My repair required a powersupplly, a logic board, and labor. I would hate to think of the costs if I hadn't purchased Apple Care.

by MacNN of this problem. Go visit Macintouch and see the miles of comments regarding the iMac G5 failures (since last fall); I just took mine in to the Apple Store to have the motherboard swapped out - my capacitors finally blew after being all puffy for months. BTW, Apple has yet to formally recognize this as a large-scale problem. They are no doubt hoping that most of the failures will occur after the out-of-the-box warranty expires. DO NOT FAIL to purchase AppleCare toward the end of your warranty on this machine!!!

this is why i still am loving my iMac G4 rev 2. 3.5 years, still working fine with no failures.

The cost of the motherboard exchange (which is covered) was around $870 (including $135 labor).

And, FYI, the Rev A of this model is the FIRST desktop that Apple ever released into the North American market whose power supply could not accommodate up to 240 volts. It is 110v only. Other regions got the robust power supply, as did the Rev B model. My Rev A is not going to have its power supply upgraded though (not until it bursts into flames anyway). Apple will not pre-emptively replace parts, even though they are known to be bad.

my fiance's brother's iMac has been in the Apple store for 2 weeks... same problem of fried capacitors. he just bought applecare in case the problems continue. he's on his second midplane and heading for a third with this capacitor issue.

I called my local (non-Apple) Apple store in C-Springs and they recognized the problem immediately. They said it was bad capacitors. I brought it in and they had it fixed at no cost to me in 2 days.

Those of us who've been around for a while may recall other Apple power supply problems, such as the infamous Mac 128/512/Plus analog board problem. I had two of those boards smoke on me. can't remember if Apple ever formally acknowledged that they had a problem. I _do_ recall that there were major changes in the Mac SE power board.

Curious, are most people who experience these failures setting their CPU to highest? One architectural firm I know has had these iMac G5s for over a year for all but the senior technicians (they have PowerMac G5s) and they have never experienced a failure with their performance set to automatic. Mind you it just doesn't take full advantage of the CPU's true power at all (only 15% faster than an EMac 1.42Ghz G4 @ highest performance) but at least their computers aren't cooking...

Yeah, it runs real hot...and is really noisy too even with the fans off it just makes that much more noise. I miss the fanless DV Macs. I Hope the intel swich resolves this..if I knew how noisy these imacs are now, i would have bought a tower.

So I only switch to the highest power when i run Logic or do Final cut. yeesh

The problem is not heat, its simply a bad batch of capacitors. My understanding is that the company that sold apple those caps doesnt even exist anymore.

Yes, heat causes them to fail more quickly, but the iMac G5 is not excessivly hot (at least the 8 we have are not), its just bad electrolidic.