Imac 27 mid 2011 power failure

Discussion in 'iMac' started by MvdLans, Sep 8, 2018.

  1. MvdLans macrumors newbie

    Sep 8, 2018
    Hy folks!
    Since a month or two my iMac 27 (3,1 GHz Intel i5) is bugging more and more.

    After a nights rest during startup it needs to reboot a couple of times before getting to work. Normally it fires up normally and during the first couple of minutes it suddenly goes dead, several times.

    Occasionally it goes dead as well after having been working properly for hours.

    I suspected the HD so I did a clean install last Friday but the problem persist......

    Disk utility says everything ok. Apple hardware test (extended) showed no errors...

    How can I figure out where the problem comes from?

    Much appreciated,


    Attached Files:

  2. MvdLans thread starter macrumors newbie

    Sep 8, 2018
  3. padams35 macrumors regular

    Nov 10, 2016
    General Troubleshooting:
    1) Do you get an error message saying that your mac unexpectedly shut down because of a problem?
    2) Have you tried resetting the SMC?
    3) Does the problem persist in Safe Mode?

    If you still suspect the Hard Drive:
    4) Have you tried bypassing the HDD by installing the OS onto an external Drive and booting from that? (or booting from a linux Live DVD?)

    If there is no error message on restart and the problem persists in Safe Mode (probable if a clean install didn't fix it) then I'd be tempted to blame the power (either flaky house wiring, a bad surge protector, or a failing PSU).
    5) Have you tried using a different/newer/better surge protector or UPS?

    If the problem persists regardless of startup mode, boot volume, and power source then I'd blame the logic board, internal PSU, or similar and suggest getting a professional diagnostic at an Apple Store or AASP (or just buying a newer machine).
  4. MvdLans thread starter macrumors newbie

    Sep 8, 2018
    Thanks Padam!

    It's getting worse and worse....... Yesterday evening after a couple of reboots it worked well for a lot of hours. This morning it needed at least 10 reboots before it's "stable".... sigh....

    Safe boot is crashing as well. Reset of Pram smc etc didn't make a difference.....

    I'll try booting from another device. But I'm not sure anymore if the problem comes from the hdd.

    I get no warnings at all, disk utility says everything is fine, like hardware test.

    Is there any program that can generate any reports about why my mac crashed?

    I'm not taking it to the apple store, the machine is to old. And in the past I "baked" twice the graphics card of another Imac and Macbook pro. So I prefer fixing it myself.
  5. padams35, Sep 25, 2018
    Last edited: Sep 25, 2018

    padams35 macrumors regular

    Nov 10, 2016
    Well, you could try looking through Console for the shutdown cause. Should be under system.log, search for 'shutdown.' Not sure how informative thats going to be though. Alternatively... hmm.

    Ok, try opening terminal and running:
    log show --predicate 'eventMessage contains "shutdown cause"'

    A previous shutdown cause of '5' was normal user initiated, '3' was a forced-restart/shutdown, '0' was a power interruption, and a negative number indicates a fault. When I tested that it took a few minutes to parse the logs.
  6. MvdLans thread starter macrumors newbie

    Sep 8, 2018
    Ok, thanks so far. I did the terminal thing and get the "128" warning so a Kernel panic. That's way to vague to solve the problem for me. But anyway I'm informed that it is not hardware related.

    I haven't opened the case but will check the led's soon @ElCani.

    Attached Files:

  7. FlorisVN macrumors 6502


    Nov 8, 2013
    I reccomend you do a hardware test, or better a Apple ASD test.
    Post result here..
  8. MvdLans thread starter macrumors newbie

    Sep 8, 2018
    Anybody got a working link to asd 3s145 for my iMac? Been searching for a while now.......
  9. FlorisVN macrumors 6502


    Nov 8, 2013
    I've got one for you np.
    send me pm..
  10. Fishrrman macrumors P6


    Feb 20, 2009
    2011's were noted for HDD failures.

    Best way to determine this is to plug in an EXTERNAL boot drive.
    If it boots right up -- that "points to" the HDD as the source of the problem.
  11. MvdLans thread starter macrumors newbie

    Sep 8, 2018
    Ok, so I've been running the ASD test and so far nothing's wrong.......... This machine is getting me crazy!! Cold startup is very troublesome = several startups, but once running she's fine!!
  12. FlorisVN macrumors 6502


    Nov 8, 2013
    i suspect your GPU is about to die..

    I was also surprised in the past that ASD OS test detected that the GPU was fine, instead in i was sure it was not ok...

    Try replacing your GPU, and beter upgrade it like I have done.. (Dell Alienware GTX765M)
  13. MvdLans thread starter macrumors newbie

    Sep 8, 2018
    I'm not convinced it's the GPU..... I've had two Macs before who suffered from a dying GPU and this Mac doesn't have the same symptoms, ak, screen of death, weird lines etc. As well I'm taking great care of cooling the GPU with SMC fan control to avoid overheating the GPU.

    I'll guess I'll open up the machine, letting it getting cold, fire it up and watch the leds for what's happening.

    EFI test did't mention any major errors as well.

    The one and only error I got was something with the Bluetooth and the Ethernet was't consequent enough. Nothing major to me.......

    Anyway, it is possible to replace the GPU on this system? On my other machines the MB wouldn't accept another GPU unless it was an original one.
  14. FlorisVN macrumors 6502


    Nov 8, 2013
    Since you have problems with Bluetooth and the Ethernet was't consequent enough i think your logic board is not stable...
    The test should give you a big failure message !

    Also I have done the same with many of these iMacs, running them cool with fan controll programms, but the AMD chip died anyway.
    Even if it was under cool temperatures.
    These GPU's are all garbage...

    2009-2011 iMacs (and even older) use standard MXM-A and MXM-B slots.
    GPU on 2011 can also be replaced...
    for more info check this thread :

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14 September 8, 2018