power problem

iMac G5 20” all in one
Processor: 2GHz Intel Core Duo
Memory: 2GB 667 MHz DDR2 SDRAM
Start up Disk: Macintosh HD

I’ve had my Mac for seven years. It is my home desktop and I am the only one who uses it. Until recently I have never had even the slightest problem with it.

Several months ago there was a power surge and the Mac was knocked out. It would not boot up after numerous tries and I assumed something was fried. It was plugged into a surge protector, which was obviously not up to the job.

The next day I tried booting again and it booted right up, almost bringing tears of joy to my eyes. (My whole life is in there.)

I went straight to Best Buy and bought an APC Back-UPS 550. All was well.

About two weeks ago I was on the web when suddenly the screen went black as if it had been shut down. There was no power surge, no power loss. All the few peripherals: printer, scanner, speakers and all clocks, lamps, TVs were still getting power. I tried bypassing the UPS. Still didn’t work. (The only things recently new and different about my configuration is the UPS and a new Western Digital external HD. It went off when the Mac went even though it has it’s own power cord to the wall.)

The next day I took it to an independent shop and explained the problem. They called the next day and said it was working fine and I could pick up. When I picked it up and asked what the problem was and the guy said that sometimes after years of service there could be a build up of static electricity or dust that can cause what I had experienced. It sounded a little weird but my Mac was working and they only charged me $50 bucks so I was feeling very fortunate, although I was wishing I had waited another hour and tried re-booting before taking it in. I came home, hooked up, booted up and everything was fine.

About two weeks later the same thing happened. I took it back to the shop. He plugged it in and it booted right up. He looked at some diagnostic screen (I wish I had paid more attention how he got there) and it said all hardware and software were OK. He was convinced that the problem was with the electric circuit in my house. I supposed he might be right even though everything else in the house was working fine. I brought it home, hooked up, booted up, no problem. Working fine.

About two hours ago it happened again. It went black and would not power up. This time I waited about two hours and tried it again. Booted right up!

As I am typing this I am anticipating it going black any second, or maybe it will wait a few weeks again.

Anybody got a clue?

Thanks

I think what's happening is something is heating up in the G5 and breaking down after a bit and that knocks out your power. It could be in the power supply or even your video card. The G5 is an old machine and likely suffering from parts old age. If you have a spare video card trying swapping the one that's in the machine out. Not much you can do about the PS except replace it.

Um, are you suggesting that he replace the video card in an iMac G5??

I would have said it's much more likely the power supply OR he's got a sensitive surge strip with a faulty circuit breaker in it.

Missed the part about the iMac. No, it would be quite difficult to replace the video card in that machine. It could well be either the PS or video card but both will be difficult to replace in an iMac G5.

The PS is easier to replace in the G5 than in some Intel models, but it will require an AASP (authorised service provider) who can get the part and do the job. Not going to be easy to find these days.

Gene, I hate to be the guy to break it to you, but you need to start shopping for a new(er) machine. The good news is that the recent iMac models are AWESOME good, and I hear a new one is being announced sometime this fall, so you should be able to find a good deal on a refurb or recent used.