Jeremy Liu

Q: iMac (Retina 5K, 27-inch, Late 2015) Randomly Restarts Without Errors

My iMac has been randomly restarting itself (about once a day) when it is idle.  Has anyone else experienced the same problem?  I found a YouTube video and it is exactly what happened to my iMac:  https://www.youtube.com/watch?v=ka7lUIeiH5E

 

I witnessed it once -- the computer was on (not sleeping) with the display off, nothing CPU/GPU intensive running.  I suddenly heard a chime and saw that the computer restarted itself.  I logged in.  There was no pop-up window.  I launched Console and did not see anything unusual before the restart.

 

More information:

 

  1. The computer is idle when restart happens.  Nothing on the computer indicates it overheats.  Display is off (due to inactivity) and fan is quiet.
  2. There is no trace of software shutdown, kernel panic or crash.  System log shows normal activities and then a sudden BOOT_TIME entry, as if someone yanks the power cord.
  3. It is not a power failure because the computer should be off if it is really a power failure.  "Start up automatically after a power failure" is not checked.
  4. It started to happen after I came back from a trip and upgraded my iMac to the latest Mac OS X five days ago.  This computer was purchased last October and I had never seen something like this until a few days ago.

 

The comments on the YouTube video suggest a total replacement, but I'm reluctant to do so if it turns out to be a software/firmware problem that can be fixed. -- The computer is heavy and the nearest Apple Store is not very close, not to mention the backup/restore efforts.

 

Thanks

iMac with Retina 5K display, OS X El Capitan (10.11.4), Retina 5K, 27-inch, Late 2015

Posted on Apr 7, 2016 6:45 PM

Close

Q: iMac (Retina 5K, 27-inch, Late 2015) Randomly Restarts Without Errors

  • All replies
  • Helpful answers

first Previous Page 20 of 20
  • by Rich M.,

    Rich M. Rich M. Sep 28, 2016 4:29 PM in response to MrFinch
    Level 1 (9 points)
    Sep 28, 2016 4:29 PM in response to MrFinch

    Sadly I just experienced my first random reboot under Sierra final build. I was really surprised as I have gone on almost 3 months without a random reboot. I also looked through the logs for the -128 error and did not find any.

  • by longtom99,

    longtom99 longtom99 Sep 28, 2016 8:50 PM in response to Rich M.
    Level 1 (18 points)
    Desktops
    Sep 28, 2016 8:50 PM in response to Rich M.

    Then it seems that it is a different issue.

  • by StigBull,

    StigBull StigBull Sep 28, 2016 11:34 PM in response to Jeremy Liu
    Level 1 (18 points)
    Desktops
    Sep 28, 2016 11:34 PM in response to Jeremy Liu

    I haven't read all 20 pages, but maybe we who experience this have something in common?

    Like software running? This is clearly not an issue with every single iMac, otherwise it would be in the news a long time ago.

     

    Me, I use the built in firewall but I have customized the rules on the OS level so I run a custom /etc/pf.conf.

     

    Anyone else?

     

    Also I had the logic board and the PSU replaced this summer, so if it's hardware related, I cannot see any component other than the Airport/bluetooth card.

     

    The BT chipset on mine is 20702B0, firmware v118c9123.

     

    The software I have constantly running are iTerm 2, Safari and Outlook 2016

  • by longtom99,

    longtom99 longtom99 Sep 29, 2016 5:45 AM in response to StigBull
    Level 1 (18 points)
    Desktops
    Sep 29, 2016 5:45 AM in response to StigBull

    For my case (-128 reboot):

    I had a MAC mini late 2012 before, then i restored the mini backup to iMac late 2015.

    THEN i had this reboots which i NEVER had before on mini!

    (Same external hardware and software)

     

    So there is some kind of combination which MAC model and OS.

first Previous Page 20 of 20