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

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

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  • 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.

  • by Dyslexicant,

    Dyslexicant Dyslexicant Oct 7, 2016 4:14 PM in response to longtom99
    Level 1 (12 points)
    Mac OS X
    Oct 7, 2016 4:14 PM in response to longtom99

    Here's my overall activities from this issue (which has solved this issue, so it currently seems).

     

    *Issue - 5k iMac 27" Late 2014 - after updating to 10.10.4 the iMac would go straight to black, no freezing, no advance warning, just off. Turning it back on required physically unplugging the power cord from the wall, waiting 10+ seconds, and then plugging it back in. At times, once logged in [and others on the login screen] it would repeat itself at random and cut to black again, or after a while cut to black again - completely random times.

     

    1) Logic board was replaced - this did not fix the issue.

     

    2) Upgrading to 10.10.5, El Capitan or Sierra did not fix it, neither did downgrading to Yosemite [via Internet Recovery].

     

    3) The Authorised Reseller Technician replaced BOTH the Hard Drive & Solid State Drive [as I had a Fusion Drive].*

     

    This seemingly has solved the issue. I've had it on a couple of days now, with no issues.

     

    *The Technician thought it might have been the hard drive as whilst I was backing up the computer on Time Machine (by playing a video repeatedly so it wouldn't idle or cut out) it literally took an ENTIRE week. Backing up 1.67 TB should not take 7 full days.Whilst I was transferring files back onto the new install after the HDD SSD replacements, the migration of 1.67TB of files took 56 hours, which, when I did the math, checked out okay.

     

    So.... I'm hoping that this now solves other peoples issues. Fusion Drives have been an issue in the past, as I know of, the previous iMac non-retina version also had a HDD & SSD replacement in a worldwide replacement scheme. So it's not an uncommon thought that Fusion Drives may be the culprit we have been looking for.

     

    I doubt I will ever upgrade this again [except for when the new filing system comes in] as Sierra is pretty stable and I don't want another issue like this happening again - I couldn't afford it when it's out of warranty.

     

    Again, I'll repeat, my issue was different to many others here, mine gave no warning and didn't randomly restart. It just cut out. Persist that they fix things, replacing the Fusion Drives would not nearly be as costly as the entire machine, so no doubt Apple will hopefully start there at a minimum. Good luck!

  • by andrewfromashton,

    andrewfromashton andrewfromashton Oct 10, 2016 1:27 AM in response to Dyslexicant
    Level 1 (8 points)
    Desktops
    Oct 10, 2016 1:27 AM in response to Dyslexicant

    Interesting.  How about physically removing the bluetooth/airport hardware from the iMac, hook up a USB mouse/keyboard, and run the machine on ethernet and wait.  If it doesn't randomly restart after 3 days, I'd say you're definitely on to something big.

     

    https://www.ifixit.com/Guide/iMac+Intel+27-Inch+Retina+5k+Display+AirPort-Blueto oth+Card+Replacement/30513

  • by smocol,

    smocol smocol Oct 10, 2016 2:43 PM in response to Jeremy Liu
    Level 1 (4 points)
    Oct 10, 2016 2:43 PM in response to Jeremy Liu

    I bought my iMac back in December went to Apple and finally got a brand new replacement.  For a while I had no issues but recently it has started to restart again, freezing at first.  Really don't know where to go from here as I love this thing but spending all this money on a faulty computer is not something I can live with.

  • by nicklear,

    nicklear nicklear Oct 11, 2016 11:16 PM in response to Jeremy Liu
    Level 1 (4 points)
    Oct 11, 2016 11:16 PM in response to Jeremy Liu

    Just received my refurb late 2015 iMac 27" (17,1) and guess what, it restarted even during the setup of the OS! Then another 4 times in the next few hours. Makes me think that's why it was in the refurb section

     

    I mainly wanted to say I am very grateful for all of you who have posted. It helps me manage my expectations and has given me some things to try. Here is what I've taken from the thread:

     

    - Some have seen good results from Sierra (I am downloading that now)
    - Most only saw results from a new logic board

    - Also worth trying trying turning off bluetooth

    - Most took months to get that new board, needing to be persistent to say the least

    - A video of the restarts might help

     

    I have an additional problem in that the machine was bought in the UK and sent to me in South Africa. They may or may not want to fix it here under the warranty (at least one store said Apple Care did work here even though they are only an affiliate, but I don't have AC just the first year warranty). They might also try to argue it was damaged in transit. They might not even have the part (logic board with M295X) as I haven't seen these BTO's on sale.

     

    Will report back in time of any results.

  • by nicklear,

    nicklear nicklear Oct 12, 2016 11:23 PM in response to nicklear
    Level 1 (4 points)
    Oct 12, 2016 11:23 PM in response to nicklear

    Sierra has solved this problem for me - so far no random reboots. And it seems to have updated the firmware it is now IM171.0105.B09 so I guess Apple did figure out how to fix the problem without replacing hardware.rateful

     

    Again grateful for this thread - I had actually been planning on staying on 10.11 as I thought it might be more stable!

  • by Leo_1971,

    Leo_1971 Leo_1971 Oct 15, 2016 1:22 AM in response to nicklear
    Level 1 (4 points)
    Oct 15, 2016 1:22 AM in response to nicklear

    Same issue with restarts.

     

    Made a clean install on a second portion with El Capitan—restarted while installation process and afterwards.

     

    Today I upgraded this clean install to Sierra ... no randomly reboots since that. When it remains stable, i'll try the solution on my main drive.

     

    Thanks for the lots of information in this thread!

  • by chrisrobinsonSD,

    chrisrobinsonSD chrisrobinsonSD Oct 18, 2016 8:26 AM in response to Jeremy Liu
    Level 1 (4 points)
    Oct 18, 2016 8:26 AM in response to Jeremy Liu

    Same as the others Sierra has solved the issue no random restart since installing it last week, stoked!

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