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FireWire · Apr 4, 2008, 11:55 PM

I wasn't sure if I should post this in the iMac forum or here, but I'm pretty sure the answer is found in the OS so..

I was using my computer tonight and out of nowhere, it just shut down by itself, without any warning or kernel panic... I reached on the back to check if the power cord had been inadvertantly pulled out but it was OK, and my iMac booted on its own without me pushing the power button. I'm using a UPS so it wasn't a power problem, as it was the only device to shut down. And I wasn't doing CPU-intensive work and it wasn't too hot so it didn't overheat.

Now I'm gonna sound dumb, because I've been using OS X for many years and I consider myself "pretty good" but... how do you read the crash logs to see what happened? I opened Console but I don't understand a thing. I searched on the web but every explanation given seems really simple, but the content of Console is really complicated. I have dozens of crash logs, which don't seem to be in any chronological order. How do I know what caused the last crash?? I will know how to read the report from there, but I don't know which one to open

CharlesS · Apr 5, 2008, 12:01 AM

Sounds like a power supply issue to me. There have been some known issues with those and iMacs. Go to a local Apple store and tell them your problem - if it's one of the known issues, chances are they'll replace the part even if the machine is out of warranty.

FireWire · Apr 5, 2008, 12:41 AM

Originally Posted by CharlesS

Sounds like a power supply issue to me. There have been some known issues with those and iMacs.

Really? I haven't heard about that!

Just to clarify things, I was talking about my Intel iMac, which I bought last fall (and is still covered by the warranty). I will investigate into that! Thank you!

CharlesS · Apr 5, 2008, 01:22 AM

Well, I don't know whether it affected the Intel iMacs or not, but it sure did with the G5 models. I had it happen to me, and know someone else who also got bitten by it. It starts out shutting off only every once in a while, then quickly gets more frequent until you can't even download one of Apple's software updates anymore before the power goes out.

Regardless, the computer just suddenly shutting off is indicative of a power supply failure, whether the model's got a history of that or not. I'd have it looked at.

Art Vandelay · Apr 5, 2008, 05:48 AM

iMac G5s made in the summer of 2005 are the ones with potentially defective power supplies. I've had to have about 35 out of 100 iMacs have their power supplies replaced so far.

Apple - Support - iMac G5 Repair Extension Program for Power Supply Issues

Cold Warrior · Apr 5, 2008, 11:35 AM

Run a hardware test; reset the SMC; and (if the issue continues) archive-install the OS to rule out an OS X issue possibly created by you or a malformed/buggy system update.

FireWire · Dec 24, 2008, 02:22 AM

Sorry to bring up this thread so long after the original post, but I've been too busy to investigate further and the problem didn't happen frequently so I just toughed it out.

I tried everything that was suggested: reset the SMC, ran the hardware test and I reinstalled the OS a couple of times since then, so I think I'm forced to take it to an Apple Store. What I'm afraid of is that they will probably say the same thing they said to asodamiac, that they could not replicate the problem since it's intermittent (and it can really take a while before it happens again) and therefore couldn't do anything for me.

Do you know if Apple can lend me a loaner in the meantime, since I can't afford to be without a computer for so long, especially with the next semester resuming soon?

AKcrab · Dec 24, 2008, 03:24 AM

Originally Posted by wasee111

this is due to virus which gives you 1 mint before shutting down. you have to restore your system to easlier stage to slove this problem. Then download AVG and install it. Or You can visit ... for more details.

FireWire · Dec 24, 2008, 04:10 AM

Originally Posted by wasee111

this is due to virus which gives you 1 mint before shutting down.

But, what kind of mint does it give me? Chocolate mint? Wafer-thin mint?

FireWire · Jul 8, 2009, 12:24 PM

Ok, the problem went away for a very long time, but since last week, my computer began to shut down by itself again. But this time I'm pretty sure heat has something to do with it. The top-left part of the case is very hot to the touch when that happens. I took a screenshot of the temperature and fan speed reading, does it look too hot to you? The first one is in °C, the second is in ˚F. Thank you!

bearcatrp · Jul 9, 2009, 08:48 AM

What kind of ups do you have? If it has multiple plugins in the back, switch to another one. Had this happen on my mac pro and a ups. But to be sure, bypass the ups and plug it in the wall to see if it still shuts down. Some ups's battery die early, still work while plugged in but if you have a brown out, looses electricity real quick. May be time to replace the battery in the ups, if it has one.

P · Jul 13, 2009, 05:49 AM

Top left is where the heatpipes end. That is a fairly high temp for the power supply, though. Electrolyte capacitors are usually rated at 85°C maximum, and if the temperature sensor is outside the actual hotspot, you might have a problem.