iMac quits without warnings, then reboots… sometimes a number of times. Suggestions

Discussion in 'Mac Basics and Help' started by atlanticza, Aug 19, 2017.

  1. atlanticza macrumors 6502a

    atlanticza

    Joined:
    Jul 18, 2008
    Location:
    Cape Town
    #1
    It’s a iMac 27-inch (mid 2011) running Sierra that’s misbehaving. So I’ve run the Apple Hardware Test - no problems found. I’ve reset Pram and SMC. It doesn’t appear to be any Apps that’s causing it, as it may reboot without any Apps open. I’ve disconnected most peripherals attached to it… still no cure. (And some time ago I had a faulty AMD Radeon HD 6970M replaced under Apple warranty.)

    The only common thread when this crash/rebooting occurs is when it’s woken up after sleeping all night long. After that, it’s mostly stable for the rest of the day. So, all in, I haven’t a clue why this is happening. Any help or suggestions would be most appreciated.
     
  2. T'hain Esh Kelch macrumors 601

    T'hain Esh Kelch

    Joined:
    Aug 5, 2001
    Location:
    Denmark
    #2
    Could be the new graphic card failing, how old is it?

    Could also be the SATA cable failing, as it would also cause those symptoms. I have had it fail in the exact same model, so it does happen. If you have an external drive you can boot from for some time, you could find out if that is the problem.
     
  3. atlanticza thread starter macrumors 6502a

    atlanticza

    Joined:
    Jul 18, 2008
    Location:
    Cape Town
    #3
    Thanks for this. the graphics card was replaced mid 2015. And I'll certainly consider booting from an external drive. Thanks again.
     
  4. Fishrrman macrumors G3

    Joined:
    Feb 20, 2009
    #4
    Is the RAM in it original?
    Or has it been replaced?
     
  5. atlanticza thread starter macrumors 6502a

    atlanticza

    Joined:
    Jul 18, 2008
    Location:
    Cape Town
    #5
    I have 12 GB installed, hardware tests and Rember reported no faults with it. But it was my initial thought too.
     
  6. Erdbeertorte macrumors demi-goddess

    Joined:
    May 20, 2015
    #6
    You could try if it occurs also with a newly created user. If it doesn't happen there it might be software related.

    Also you may try Etrecheck and post the report here. http://etrecheck.com

    It could show what might be wrong with your Mac mostly software wise.
     
  7. atlanticza thread starter macrumors 6502a

    atlanticza

    Joined:
    Jul 18, 2008
    Location:
    Cape Town
    #7
    Thanks for your suggestion. Found a couple of orphan files. Otherwise OK.
     
  8. atlanticza thread starter macrumors 6502a

    atlanticza

    Joined:
    Jul 18, 2008
    Location:
    Cape Town
    #8
    Tried all suggestions and eventually took it into an Apple service centre. Tested for a week there. No problems and could not repeat the "fault" so it's back with me and appears to be OK. Mysterious.
     
  9. Fishrrman macrumors G3

    Joined:
    Feb 20, 2009
    #9
    Again, I'd suspect the RAM.
    Is the RAM that's in it now the "factory original"?
    Or... has it been replaced?

    If it's been replaced, do you still have the original RAM?
    Have you tried putting it back it, and running that way?

    Have you tried taking the RAM out, cleaning the contacts, and replacing it?
     
  10. atlanticza thread starter macrumors 6502a

    atlanticza

    Joined:
    Jul 18, 2008
    Location:
    Cape Town
    #10
    Hi, Apple supplied the RAM and it's new. And when I took the iMac in, they gave everything a thorough clean, and could find nothing wrong even after hours of stress testing... so I'm holding thumbs...
     
  11. atlanticza thread starter macrumors 6502a

    atlanticza

    Joined:
    Jul 18, 2008
    Location:
    Cape Town
    #11
    ... well holding thumbs wasn't enough: it's doing it again! Seems to not like being woken up from Sleep mode after pressing Esc early in the morning. After a couple of reboots it's happy for the rest of the day. Strange. Could it be a peripheral like its wired keyboard?
     
  12. nickm11 macrumors newbie

    Joined:
    Dec 30, 2015
    #12
    Try creating a system on an external HD or partition and run off of that for awhile. My guess is a kernel problem.
     

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