11-05-2007, 01:01 AM

My computer stalled out a few days ago and would not restart after i forced a shut down. It stops at the startup screen with the spinning icon and goes no further. It will not start in safe mode, either. I also tried to re-install the system software and it froze. What is going on here?

11-05-2007, 03:03 AM

It's impossible to diagnose without more information. It could be almost anything... If it's a hardware fault it could be a bad processor, a dying logic board, a bad stick of RAM, or a dying power supply, just to name a few things.

Some of the G5 iMacs are notorious for logic board failure due to Apple's decision to use very low quality capacitors on the board (interestingly enough, many PC motheboard manufacturers had encountered this problem-and corrected it-LONG before Apple released the G5 iMacs. It was a major issue, one that was very widespread and well-known. Apple should've known better). These capacitors have a defective electrolyte formula that causes the buildup of gases in the capacitor. This causes the capacitor to bulge and leak, which in turn causes them to drop out of spec or fail to operate completely. This then leads to all kinds of weird problems, and eventually to complete logic board failure.

Pictures, if you're curious, of what these capacitors look like (courtesy of my own dead iMac G5 logic board):


AAAAAAAAANYHOW...., back to your problem. Have you reset the SMU and the PRAM? If not, you should start with those.
Resetting the SMU
Resetting the PRAM

If you try those, and it still has this problem, we'll need some more information... Like when did it start? Was it just after you installed a piece of software, or just after you moved the machine around or anything? Has the board in this machine ever been replaced due to bad capacitors? Does it make any strange noises? etc.

11-05-2007, 06:48 AM

As Geeky says, we haven't much info to go on to help you out. Try what Geeky suggested.

Another thing to try is shutting down your iMac, unplug it from the electrical outlet in the wall and let it sit for 5 or 10 minutes, then plugging it back in: this helps the capacitors to drain.

And I would suggest you also look at these Apple Knowledge Base articles and compare your serial number with those on these lists (maybe your iMac G5 is part of a recall):

- iMac G5 Repair Extension Program for Power Supply Issues

- iMac G5 Repair Extension Program for Video and Power Issues

11-17-2007, 08:50 PM

I tried everything, including resetting the SMU and PRAM, it still won't start. The machine hasn't been moved recently, I haven't installed anything, and nothing strange happens. It just sort of stops during the startup process. Reinstalling system software freezes, Disk First Aid errors. I just don't get it!

11-17-2007, 08:53 PM

How old is your iMac G5? As Geeky showed, the older models had some capacitor issues like some PC motherboards did. There was a recall by Apple at one point. What are the specs on that iMac G5?

11-17-2007, 08:56 PM

Yep posted the links to those recalls. All the OP has to do is check his serial number and compare them to the ones on the lists...