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iMac turns off suddenly

4973 Views 22 Replies Latest reply: Sep 11, 2013 9:22 AM by skskmusic RSS
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TempusThales Level 2 Level 2 (165 points)
Currently Being Moderated
Jul 22, 2011 8:20 PM



Since upgrading to Lion I have had my iMac 3 times tunr off right in the middle of working.  Different apps all the time.  It never has done this using snow leopard.  Just started after I upgraded to Lion.  Is there anywhere in the console to look at logs to see what is happening or is anyone else haveing a similiar issue?



  • RodneyW Level 4 Level 4 (3,030 points)
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    Jul 22, 2011 9:01 PM (in response to TempusThales)

    I am not having a similar problem.  However I would recommend that you look at the "All Messages" of Console at the time that it shuts down.


    If it just turns off without warning rather than crashing ... It sounds more like a power supply issue than an operating system issue though.

  • hmbgus Calculating status...
    Currently Being Moderated
    Jul 25, 2011 7:11 AM (in response to TempusThales)

    Identical experience but with a first gen 15" unibody MacBook pro...  Will turn off with no warning multiple times a day. Started after "upgrade" to lion.  Never happened before.

  • RodneyW Level 4 Level 4 (3,030 points)
    Currently Being Moderated
    Jul 25, 2011 4:07 PM (in response to TempusThales)

    After further digging, and a bit more time in the forums, it seems that there is an issue with Lion and some discrete graphics cards.  IF you set your Mac to ONLY use the integrated graphics (using a tool such as gfxcardstatus, or the built in preferences on the older MBP), then you may find relief until Apple puts out an update.

  • Maria Fernanda Affonseca Calculating status...
    Currently Being Moderated
    Jul 25, 2011 4:35 PM (in response to RodneyW)

    My Macbook Pro has also gone off twice since I upgraded.  Actually it seems like the screen goes off, not the computer.  But the only way to make it come back to life is by force-restarting the computer!


    Come on, Apple!  Release an update NOW!

  • Ebow1970 Calculating status...
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    Jul 27, 2011 8:17 PM (in response to Maria Fernanda Affonseca)

    I have experienced this black screen issue almost ten times since the upgrade to Lion.  I am not finding much help out here.  This is a very unstable platform.

  • RodneyW Level 4 Level 4 (3,030 points)
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    Jul 27, 2011 8:22 PM (in response to Ebow1970)

    Have you tried gfxcardstatus?  DId it help?

  • Ebow1970 Level 1 Level 1 (0 points)
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    Jul 28, 2011 1:27 PM (in response to RodneyW)

    I installed the gfxcardstatus yesterday, had it set to integrated only, and experienced a black screen followed by an immediate shutdown trying to open the email from the support community.


    Is there any way of backing out the Lion upgrade?

  • RodneyW Level 4 Level 4 (3,030 points)
    Currently Being Moderated
    Jul 28, 2011 3:36 PM (in response to Ebow1970)

    Dear ebow1970,


    You can always restore the backup that you took before you installed Lion.


    1) If it is a Time Machine backup boot from your Snow Leopard install disk, and select Restore from Time Machine Backup


    2) If it is a bootable clone, simply restore the clone back to your internal hard disk





  • \'cintosh Level 1 Level 1 (65 points)
    Currently Being Moderated
    Aug 13, 2011 12:19 AM (in response to TempusThales)

    Have you guys tried resetting the PRAM?


    Shut down your computer

    Unplug all of the periffirals and the power cords

    Leave unplugegd for 30 seconds and plug back in

    When starting up, hold down Option+Command+P+R until the screen goes black

    When the computer reboots let go of the keys


    It seemd to have solved my issue momentarilly but im digging around for more information online

  • Carolyn Samit Level 10 Level 10 (84,160 points)
    Currently Being Moderated
    Aug 27, 2011 5:40 AM (in response to TempusThales)
    I have tried resetting everything


    Did that include  Resetting the System Management Controller (SMC)  ??

  • Mihalis Tsoukalos Level 4 Level 4 (2,015 points)
    Currently Being Moderated
    Sep 6, 2011 2:07 PM (in response to TempusThales)

    My iMac (27'' C2D 3.06Ghz) did that earlier today.

    I have Lion since Friday.



  • Calculating status...
    Currently Being Moderated
    Sep 7, 2011 9:32 AM (in response to TempusThales)

    Same for me (1 year old 27" iMac). Never done this before & has been randomly shutting down for weeks now. It started out very bad - every few minutes in the days immediately after I installed Lion, now it's about 1-2 times per day (or less). I also have a Macbook Pro that has no problems at all.

    I have spent hours on the phone with Apple - tried every test & nothing has solved the issue.

    They suggested it could be old incompatible software, so I have basically stripped my mac of any software I no longer use (and now there is nothing on the iMac that isn't in the laptop). I used Appcleaner to make sure all component parts of old software was removed.


    I also use Cocktail to complete a complete system maintence daily (repair permissions + clean out caches etc).


    Between those two actions, the computer is at least usable now, but its certainly not fixed.

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