mikestan56

Q: iMac shuts down randomly for no apparent reason

In late August of this year, after the plug came out of the back of my iMac when I was attempting to adjust the angle of the screen while the computer was on, the computer began shutting off for no reason while on. I took the iMac to the Apple Store in El Paseo, in Palm Desert. They replaced the 3 TB fusion hard drive saying that there had been a history of problems with this. I received the iMac back and shortly thereafter began to shut down once again for no reason. I brought it back to the Apple Store and they deleted some software and removed some software that were automatically engaging at startup. The iMac began to shut down for no reason once again. I brought it back in and they ran a full diagnostic test and could not find any problems. It worked for a while and then began to shut down for no reason again. I brought it back in to the Apple Store in this time I was advised that there are going to run more extensive hardware testing, running it through longer cycles etc. They could not find the problem and suggested that it was likely an effect of peripherals I had connected to the iMac. I disconnected all the peripherals from the iMac and began testing them one by one over time. The iMac still shut down for no reason at random times. I ran the computer with no peripherals connected at all, and it still shut down for no reason. I have run Apple diagnostics and it found no trouble. I have run malware detection software and it found some things that were then deleted. I did this very early before I even brought to the Apple Store. I ran antivirus scans, full scans on the iMac and it found no infection. I also ran fan control software to see if the iMac was overheating and even with the fans at the full rpm setting, the iMac still shut down at random times. I used a rocket air blower that I used to remove dust from my camera lens to try to blow through the back vent and the bottom screen vents to free that of any buildup of dust, and it still shut down for no reason. What could possibly be the issue with this machine after all the testing and interventions that have been done?


Late 2012 iMac - Quad Core Core i7- 16GB, 3TB Fusion Drive

iMac, OS X Yosemite (10.10.4), Mac (27-inch, Late 2012) 3.4 GHz

Posted on Nov 3, 2015 3:55 PM

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Q: iMac shuts down randomly for no apparent reason

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  • by tabrings,

    tabrings tabrings Nov 25, 2015 2:53 PM in response to mikestan56
    Level 1 (0 points)
    Nov 25, 2015 2:53 PM in response to mikestan56

    A few weeks ago my iMac (27-inch, Late 2012) started to not wake up from sleep in the morning. The only way to re-start it was with a SMC reset. Then it started blacking out randomly during the day and also would only restart with a SMC reset.

     

    To see if I could identify the conditions that would trigger a blackout, I installed the "System Monitor" app from the App Store and started monitoring the temperature, fan speed, and cpu load, as I used the computer throughout the day. The random blackout continued and I could not find any correlation between temperature, cpu load, or fan speed, and the blackouts.

     

    After one of the blackouts I re-started the iMac holding down the D key in the keyboard to boot into Apple Diagnostics. The quick test did not find any problems, but when I selected the extended test, it seemed stuck at 34 minutes during the pass 1 of the memory check, even though it was running for more than 2 hours. I tried stopping the test but it did not respond to the mouse or keyboard. As it did not respond to the power on button, I pulled the plug.

     

    I pulled out the 8 GB memory upgrade I had installed about 2 years ago and left only the original 8 GB from Apple. I rebooted into Apple Diagnostics again and this time the extended test completed in less than one hour and found no errors.

     

    At least in my case, it seems that the problem was caused by bad memory. Now, with only the original 8 GB that came with the iMac, it has been working as expected for more than 2 days. The display brightness is set to automatically adjust, and the computer sleep and display sleep functions have been working as expected.

  • by brucefromfort pierce,

    brucefromfort pierce brucefromfort pierce Nov 26, 2015 8:13 AM in response to mikestan56
    Level 1 (0 points)
    Nov 26, 2015 8:13 AM in response to mikestan56

    I had a similar problem with my iMac.  Some time ago, I added two 4GB memory sticks, purchased from an on-line vender.  After Apple Support and I had tried everything else, I bought two new memory sticks and replaced the ones that I had purchased earlier.  Problem solved.  Apparently, there was some sort of minor malfunction in one of the memory sticks that caused the periodic shutdowns.

  • by babowa,

    babowa babowa Nov 26, 2015 8:30 AM in response to brucefromfort pierce
    Level 7 (32,024 points)
    iPad
    Nov 26, 2015 8:30 AM in response to brucefromfort pierce

    In my case, I have not added any RAM to the factory installed 16 GB (2 x 8). And, the black screen/unresponsiveness is mostly when I have anything attached to USB ports 1 and/or 2 (from left). The Capture Data files were uploaded to Apple, so I will see what their Engineers determine (if anything); because of the holiday and the fact that most of them are off this week, I don't expect anything before early/mid next week.

  • by John Galt,

    John Galt John Galt Nov 29, 2015 7:01 PM in response to mikestan56
    Level 8 (49,085 points)
    Mac OS X
    Nov 29, 2015 7:01 PM in response to mikestan56

    Thanks for that link mikestan56. I have not read every single post because so many of them understandably just want to relate their own tales of misery and / or just rant about the issue which makes it a challenge to find anything useful.

     

    However, I did find this one ("Link to this post" doesn't seem to work for me):

     

    blinkypete wrote:

     

    An Additional Update:

     

    Since obtaining my system from repair (i.e., power supply and power cord replacement) over a week ago, I have not experienced an intermittent shutdown.

     

    I suggest obtaining the shutdown code that is associated with an intermittent shutdown. In my situation, as soon as the Genius Bar representative had this code, he was able to make a diagnosis and propose a repair solution. Granted, I am still under Applecare and that may have been a factor in his little hesitation to repair the system. Prior to obtaining this code, the Genius Bar was unable to replicate the issue.

     

    Finally, although I may or not be in the clear and that each situation has similarities and differences, I'm thus far satisfied with how Apple, specifically Matt (Genius Bar Representative) at the Northbrook, IL location, handled my system's issue.

     

    As I wrote a long time ago that shutdown code (zero) indicates a power interruption that points to a power cord as one obvious component, and the power supply, another. You got a new power cord but blinkypete replaced both, and since he hasn't posted anything subsequent to the above I can only assume his problems have been resolved to his satisfaction.

     

    The point is that someone has to do something to advance troubleshooting toward an ultimate solution. So far, Apple hasn't done anything productive for you toward that end. A Mac is a complicated piece of hardware, and something is obviously defective with it. Whatever that is needs to be replaced. Until someone starts replacing some parts, even if you have to pay for it, you're not going to get anywhere.

  • by mikestan56,

    mikestan56 mikestan56 Nov 29, 2015 7:21 PM in response to John Galt
    Level 1 (4 points)
    Nov 29, 2015 7:21 PM in response to John Galt

    Thank you again John for your assistance and feedback. I was one day away from mothballing the iMac and buying a new HP PC. I have an appointment with Apple this Friday, I will demand a power supply replacement. If that does not solve it, then its the HP and migration to PC. Apple has lost its edge...

  • by John Galt,

    John Galt John Galt Nov 29, 2015 8:21 PM in response to mikestan56
    Level 8 (49,085 points)
    Mac OS X
    Nov 29, 2015 8:21 PM in response to mikestan56

    Please let me know what they decide to do. Even if you had to pay for a power supply replacement you'll be doing something.

     

    ... buying a new HP PC

     

    Good luck. The last HP I owned literally spent more time in the repair shop than I had it for my own use, until its warranty mercifully expired and I threw it in the trash.

     

    As for their user support forum, judge for yourself: http://h30434.www3.hp.com/t5/Laptop-and-Notebook-Computers/ct-p/Notebook. You'll find a lot more users giving up on them and moving to Macs than you will find users on this site going the other way. Enjoy.

  • by Yukka21,

    Yukka21 Yukka21 Dec 30, 2015 1:15 PM in response to John Galt
    Level 1 (0 points)
    Dec 30, 2015 1:15 PM in response to John Galt

    Any idea what a shutdown code -128 may mean?

  • by Jan Sondergaard,

    Jan Sondergaard Jan Sondergaard Feb 11, 2016 11:50 PM in response to mikestan56
    Level 1 (0 points)
    Feb 11, 2016 11:50 PM in response to mikestan56

    I understand your frustration, but I can tell you that moving away from PC ****, and in particular a bad experience with HP desktops, is the best decision I have ever made.

  • by Jan Sondergaard,

    Jan Sondergaard Jan Sondergaard Feb 12, 2016 12:01 AM in response to tabrings
    Level 1 (0 points)
    Feb 12, 2016 12:01 AM in response to tabrings

    So, I am joining this thread with similar problems. The random shut downs started 5 days ago. iMac (27-inch, Late 2012) recently was upgraded with Crucial memory and the last couple of days I have been reading many articles on "memory upgrades" causing shut downs. Fortunately, I have the original 8GB Apple memory, but the shut downs are persisting.

     

    I wonder if we are all subject to Apple planned obsolescence?

     

    Now, one outstanding wildcard is the 3TB Fusion Drive recall. I have not had that done yet, so maybe it's time I give that a try.

     

    Thanks to John for all the help re. error codes in the system console. I am also a case of error code 5:

  • by Beolion73,

    Beolion73 Beolion73 Apr 23, 2016 7:52 PM in response to Jan Sondergaard
    Level 1 (4 points)
    Apr 23, 2016 7:52 PM in response to Jan Sondergaard

    Same issue here, started 2 months ago and I tried to wipe the HDD and start all over again. And am using a new powercord.

    I guess the power supply is probably at fault, and I can only hope that Apple will acknowledge that there is a problem here.

    iMac 27", late 2012, i5 3.2 GHz, GeForce 680MX 2GB, bought in Denmark.

  • by billy55555555,

    billy55555555 billy55555555 May 10, 2016 2:41 AM in response to Beolion73
    Level 1 (4 points)
    Desktops
    May 10, 2016 2:41 AM in response to Beolion73

    Yup. I've tried reconfiguring the RAM, wiping HDD, reinstalling OS X, forcing my fan to cool things down. Very frustrated, and for the first time in two decades I actually don't think I want another Mac after this.

  • by oomoot,

    oomoot oomoot May 26, 2016 9:58 AM in response to mikestan56
    Level 1 (4 points)
    Desktops
    May 26, 2016 9:58 AM in response to mikestan56

    Mike have you got your problem sorted out?

    I have the exact same machine with the exact same problem (Late 2012, 27 inches, i7 3.4GHz, 3TB Fusion, 680MX, 32GB of original Apple RAM)

    I also had a history of acidental cord pulling but I thougt it was because of the 3TB which I got replaced.

     

    If you got it solved by replacing the power supply please let us know so that I'll save myself extensive trips to Apple Store.

  • by WODD,

    WODD WODD Jul 17, 2016 12:00 PM in response to mikestan56
    Level 1 (4 points)
    Desktops
    Jul 17, 2016 12:00 PM in response to mikestan56

    I have the same problem. Same Computer with 32 GB Ram. I have taken it in to Apple, who states that it never shuts down for them. I had all RAM replaced, I had motherboard replaced. Just shut down again, I am posting this on my PC. I have taken it in four times, and they claim no problem. Every time it shuts down. Also I get an out of memory error as well that no one can explain.

  • by slevin182,

    slevin182 slevin182 Aug 21, 2016 2:39 PM in response to WODD
    Level 1 (4 points)
    Aug 21, 2016 2:39 PM in response to WODD

    I had exactly the same problem as you and apple didn't give me a solution.

  • by babowa,

    babowa babowa Aug 21, 2016 6:40 PM in response to slevin182
    Level 7 (32,024 points)
    iPad
    Aug 21, 2016 6:40 PM in response to slevin182

    This may not apply here, but I had a problem with my iMac not waking up (and silently/in the background shutting down) whenever a) I had one of my external hard drives plugged in and b) allowed it to go to sleep. When I wanted to wake it, it would not work - it was dead and the power button did not work (nothing else did either). I had to unplug/plug it back in. This only happened when I had a hard drive attached. It was finally determined that Apple made a change in the OS late last year which resulted in the malfunctioning of the external enclosure's chipset (plug). Once I got new hard drives with different chipsets (OWC replaced them as they were still under warranty and they were working with Apple to get a handle on the problem), I haven't had a problem since.

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