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  • Jason Kim Level 2 (165 points)
    My late 2007 iMac randomly restarts, too. I reset PRAM and SMC with no improvement. Suspecting I had bad power supply hardware, I took it to the Apple Store and they tested it hard for 5 days nonstop. It never restarted. I took it home last night and got a random restart this morning.

    I have noticed that the restart often happens just a few minutes after I get a "software update available" message and I don't click "install and restart now". But the computer does not shut down apps and log out gracefully, it just suddenly blinks out right in the middle of whatever video or music is playing. And when it comes back online, the software has not been installed, so I really don't know if these things are related. Furthermore, while the computer was in the Apple Store, software update offered an update and I intentionally did not click "install and restart now" just to see if it would restart. It did not.

    My current thinking is that if the iMac is okay, then the circuitry in my 65 year old house may be to blame. I know the circuit that the iMac is on is shared by the kitchen downstairs because in the past I've blacked out my office by running the toaster oven. Nothing else in my office is affected when my iMac restarts, but perhaps I'm experiencing minute brownouts on the circuit that only affect the computer... is this possible? I'm thinking of buying an uninterruptible power supply (UPS) to even out the voltage.

    The problem is, I had the "auto-restart after power outage" option turned off when I experienced the restart this morning. So I'm not so sure if my house circuitry is the problem. If it were, you would think my computer would have just shut down and not restarted.

    Does anyone have their spontaneously restarting iMac hooked up to a UPS? If so, we may rule this possibility out.


    P.S. I have factory installed RAM, no overheating issues, and no peripherals attached other than the keyboard/mouse and a Westell router.
  • Jason Kim Level 2 (165 points)
    In the days since my last post, my computer went from 1-2 restarts a day (usually within the first 5 minutes of waking from sleep) to 4-5. At one point, the thing would not even boot up at all. Fortunately, when I moved it to another outlet, it did boot up again... probably because the SMC had been reset from unplugging it. Unfortunately, it kept restarting at the new location.

    I finally went to Best Buy and bought a $90 UPS with automatic voltage regulation. So far, so good... no restarts in the first few hours. As I mentioned, I usually get my restarts within the first 5 minutes of waking the iMac from sleep. I have slept it and wakened it several times with no problems.

    So if this works out, it would seem the voltage in my house has some kind of instability. Why it does not affect my other appliances, including my TV, stereo, my old iMac, and my PC, does not makes sense to me. Why it did not affect this iMac until after two months of use also doesn't make sense. It pretty much ***** that my $1500 Mac is totally dependent on a $90 third party product that is only supposed to last for 3 years. I feel the iMac has an overly sensitive or poorly installed power supply and should be fixed. But I have no way to prove it.

    Part of me almost wishes that the UPS would not have solved the problem and that the computer would go so bad that it wouldn't boot again. At least then I'd have a clear case for replacing or servicing the machine.

    We'll see if I'm back here in a few days...
  • Boy of Wonder Level 1 (25 points)
    If your iMac is still in the AppleCare Protection period, then go and replace it!
    and one more thing, 10.5.2 is out so download it.
  • Jason Kim Level 2 (165 points)
    It just restarted again. ****!
  • Jason Kim Level 2 (165 points)
    After that last restart, I had a good two days of no restarts. Then, this morning, I woke up the iMac from sleep and got three bad restarts within the first 10 minutes. Bad meaning that instead of restarting immediately, it was dark for about 10 seconds before it rebooted.

    Guess I'll be returning the UPS to Best Buy and taking the iMac back to the Apple Store.

  • wickhama Level 1 (0 points)
    Hello, I just received my refurbished Aluminum iMac last saturday, and it too is experiencing random shutdowns (or blink-outs as some else here put it). I found a discussion thread (somewhere around here) that talked about using smcFanControl to reset the speeds of the fans, and upon installing it, the temps reported were around 100 - 102 degrees Fahrenheit (this was right after a random shutdown). So I bumped the min rpm speeds up by ~ 300% on each, and right away the temps started coming down. Now I'm wondering what the safe temps should be so as to set the fans appropriately, and I'm not sure if this will fix the issue long term either. AND I shouldn't have to do the anyways!!!
  • wickhama Level 1 (0 points)
    I was just looking at the tech specs, and here are the operating temps:

    "Operating temperature: 50° to 95° F (10° to 35° C)"

    which means that my imac was operating above it's max! doh! apple, you need to figure this one out, or you'll have a bunch of melted iMacs on your hands!
  • Jason Kim Level 2 (165 points)
    When I took my iMac to the Apple Store the first time, they checked the temperature and said it was not overheating. They also ran the processor hard for 5 days, heating up the chips, and there were no restarts.

    In my house, the restarts generally occur within the first few minutes after waking from sleep, so if anything, the machine is cold not hot when the problem arises. My house is not below 50 degrees, so running cold is not the problem either... and I doubt that would cause a restart.
  • wickhama Level 1 (0 points)
    my home is usually kept at around 75 - 80 degrees Fahrenheit, so it's rather warm, but my Sawtooth G4 has never had a problem with that. and like i said before, it was at 100 degrees F (and climbing), which is over the allowable max temp (per the tech specs), so i can see why it did shutdown. i just wonder why the os is allowing the fans to spin at such a low rpm.

    i need to mention, in full disclosure, that i discovered the wall socket the computer was plugged into is faulty. however, the shutdowns continued after i moved to a known good socket. and there still is the issue of the overheating.

    i think i'll either call up Apple or go to one of the numerous apple stores in my neck of the woods to see if they have any answers. i'd hate to see someone like my dad (who's a new imac user too) to experience this and get an unnecessarily bad view of the mac/apple because of this.
  • iMac 7.1 Level 1 (0 points)
    Mine does this to. We got it in late 2007 and still does this. Also it is plugged in to a ups and battery backup
  • wickhama Level 1 (0 points)
    arghh! so last night, the machine was fine, and i upped the fan rpm settings to get it a bit cooler, since it still likes to run ~ 91 - 95 degrees F. i did some more on my taxes, was moving files from the G4, no problem. the case itself felt cooler to the touch (on top), so i crossed my fingers and hoped it would stay 'fixed'.

    so this morning, i pressed the iMac's power button (btw, the power button location is very poor design for people who can't lean forward and reach around the case, such as people with various muscle diseases) in anticipation of the machine starting, but the only thing i heard was the whirring of the hard drive (my guess), nothing else. so i pressed it again - nothing. so i went through the smc reset process - nothing. tried again - nothing. i had given up and gone on to do something else, when ~ 5 minutes later, the darn thing just powers up! my wife started using it to check her email, not knowing what had just transpired, so nothing seemed the matter to her. this happened to me the first time i tried to power up, but since it hadn't happened since, i thought it was just new machine funkiness. so now i really need to get to some apple support person to help fix this. arghh!!
  • wickhama Level 1 (0 points)
    k, update on the imac. after i came home, the machine wouldn't start at all, and the next morning had it doing the same thing - nothing. so i made a genius bar reservation, took it in, and they declared it DOA, which means that i need to send it back and they'll send me a 'new' one. i'm not sure if that means 'new' as in 'new' or 'new' as in 'refurbished', but i just want the darn thing to work. i'm waiting for the shipping label to return it, so once that is delivered, i can get the aluminum brick back to apple. sigh
  • wickhama Level 1 (0 points)
    so an update on my iMac problems. i finally got the return label (i had to wait 3 days!), and i eagerly sent off my DOA iMac, expecting that after it was scanned in at the Fedex pickup location, the replacement would be sent. well, it took another day for the info to get to Apple, so the replacement has finally been sent, and it should be delivered today. here's hoping that it runs fine!
  • apenaroks Level 1 (15 points)
    strange, when I put my mac to sleep, every five minutes, it wakes up, but the screen remains off. Then after another 5 minutes, it will go back to sleep; and so on and so forth. Brand new also.
  • wickhama Level 1 (0 points)
    yeah, that is interesting. perhaps it could be an energy saver issue? have you updated with all the latest updates?

    i just setup my newly received 2nd iMac, and everything went smoothly, though it too started heating up. after installing smcfancontrol, things started to cool down, and there haven't been any spontaneous restarts. i'll have my fingers crossed for awhile until i can feel i can trust this machine.