27 iMac (2012) crashes and requires smc reset to turn on

My late 2012 iMac, i7 16gig RAM 27 inches keeps shutting down. It looks like as if it was unplugged. Happens randomly. Sometimes while playing Diablo 3, surfing facebook or using iphotos or other apps. Seems to not crash if just left on overnight and not been used.


In order to turn it on again I have to unplug it from the power line for like 30 seconds, only then it starts.


I have the settings set to restart on power failure, but it does not.


Happened a few times a few months back. I have installed a surge protector and it worked fine for like a month or two. However last 2 days it has shut down like 10 times...


Help would be greatly appreciated. I suspect hardware failure.

iMac (27-inch, Late 2012), iOS 7.1.1

Posted on May 5, 2014 9:44 PM

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Posted on Oct 26, 2017 3:46 AM

Hi there - hope I'm on the right thread for this reply.


I recently suffered the same issue for over a week whereby my late 2012, 27" iMac (1TB fusion drive) would unexpectedly shutdown like someone had yanked the power supply cable from the back. I could only get it restarted by removing the power lead for 15 secs, plugging back in and waiting 5 secs before starting up - and apart from a Chrome "unexpected shutdown" message, you wouldn't have known that it had shut off.


I spent a few hours on to Apple Support trying various solutions (Diagnostic test, MemTest, SMC/PRAM resets, Sierra reinstall etc).


By trial and error, I eventually identified the problem's source as being my Satechi 7 port USB 3.0 hub which had 2 x Porsche design (1TG and 4 TB) external HDD's attached, along with 2 x charge/sync docks for iPad and iPhone. Since I removed the USB Hub and plugged the peripherals into the back of the iMac, I have had no issues whatsoever - and my pride & joy is back working like a dream.


I hope this update helps

574 replies

Jan 15, 2016 3:53 AM in response to Annecarter

to Annecarter:

I do feel your pain here. Though, one positive point I can get is that you had the power supply changed and that provided you about 4 months free from any issue, is that correct? If so, it really sounds like this could be the source of the problem, but also that the power supply component is relatively unstable since it degrades so quickly.

Also, I remember thinking initially about getting a mini that would use the iMac as a slave for the screen, but I don't consider it as a solution anymore (shutdown would still happen as the iMac still runs in the background). Though, plugging the mini to a TV could be your solution, but it is out of this conversation scope.


to Joe5000:

Yep, I had understood you were 'lucky' to get a swap for a brand new one(not that you haven't suffer for it).

I was just wondering what was the ultimate argument that won over the heart of the Apple representative, and if you still were under the 1 year guarantee or the Apple care plan.

to FalseAlbie134:

So you are intending to change the power supply yourself, with another component than the one used by Apple for this iMac. I have to say I would not dare trying to do it myself, easy on a PC but totally a different story on those iMac.

How did you get the power supply unit, how is it different from the original one?

Did you get Apple to change your power supply once before, without success?

In any case, all the best to you if you are definitely proceeding to the change yourself, and keep us updated please ;-)


I am expecting a call from Apple today, and will provide feedback to you as to what is their take on changing the power supply while this one seems so moody.


Jan 15, 2016 7:07 AM in response to laurent.d

So, as expected from talking to an advisor for 40 minutes, they can not do anything, only redirect you to the Apple Store (my only success was to get the advisor to sympathise with me), and this regardless of how many people are affected.


I guess it leaves me with no choice but to go visit the Apple Store, explain again the issue, and stress on the fact that power supply could be the cause.

I shall also give a link to this discussion.


Given that nothing would be found and that we would opted this time to get the power supply replaced (paying for it), I was wondering if there is any kind of guaranty on the new component, so I looked at the retail and repair terms and conditions and I understood that there would be a 90 day warranty, do you agree with my reading of point number 5 (french version is similar)? If so, that would give around 3 months time where if the issue resurface, the next repair is free, wouldn't it?

Jan 15, 2016 8:36 AM in response to Lagoiski

  • Case Number **** from July 26 (reset SMC & PRAM)
  • Case Number **** from July 29 (Genius Bar Appt - no hardware problems were found and issue did not replicate itself)
  • Issue did not reappear for a few weeks.
  • Case Number **** from August 19th - Talked with Senior Steve N. - reinstalled OSX (without a full disk erase). Emailed him back on August 20th to say the problem was not resolved, no answer. Emailed again on August 27th, no answer. Left voicemail on August 27th no call back.
  • Case Number **** from August 30th - Talked to senior Pete H. Removed all apps that were automatically loading at startup.
  • Case Number **** from August 30 - Talked to senior Jonathan B. Reinstalled OSX (twice) after a complete disk erase. Set up as a new computer with no transfer of old files. Got stuck in "setting up mac" both times.
  • Case Number **** from August 31 - Talked to senior Brandon D. who told me to hard restart without reinstalling. System booted up fully. Still experienced a random shutdown within 15 minutes of working in Safari and Photos. Brandon told me that it has to be a hardware issue and to make another appointment at the genius bar. Case number ****: September 2 - Genius Bar Appointment. Replaced PowerSupply. Ready for pick up on September 7th.
  • Issue did not reappear for 4 months. Now starting on January 9 (exactly 4 months after power supply was replaced) it has happened 3 times in the last week. Genius bar repair set for January 16th. Will Update after I see what they say.

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Jan 15, 2016 11:07 AM in response to Annecarter

Thanks Anne for your summary. I read that you had only the power supply changed, and once.

I also read that you spent a long time before going toward the hardware track, hence even more frustration.

As per this change fixed the computer for 4 months, and given this is the only thing that was replaced, it really seems to point to this component being the culprit.

Good luck with the Genius bar meeting, I'll have to do the same on my side (convincing my dad first it worth trying).


On a separate note, I can not help noticing the irony that the host of this discussion keeps editing some of the posts (legitimate reasons I am sure) but on the other side, Apple have not yet put any comment on the forum nor seems to acknowledge the existence of this issue, still, one of them is reading ;-)

Jan 15, 2016 12:31 PM in response to laurent.d

1] My case number goes back to March 2015: *** *** *** Same late 2012/2013 27" Core i7 iMac. Three times to Genius Bar for ineffective repairs, now on my third AppleCare Senior Adviser. Brought it back for the fourth time to Apple Store in Short Hills NJ, this time with a print of all fifteen pages of this thread.


2] The AppleCare Warranty issued in 2013 reads, in part, as follows: 3. What is Covered? 3.1 Hardware Service. If during the Coverage Period, you submit a valid claim by notifying Apple that (i ) a defect in materials and workmanship has arisen in the Covered Equipment, or (ii ) the capacity of a covered iPod battery etc. . . , Apple will either (a) repair the defect at no charge, using new or refurbished parts that are equivalent to new in performance and reliability, or (b) exchange the Covered Equipment with a replacement product that is new or equivalent to new, in performance and reliability, and is a least functionally equivalent to the original product. . . "


3] If Apple, in the case of these defective 27" iMacs, replaces the power unit with another unit which subsequently fails, as seems to be the case with many of the contributors to this thread, has Apple honored its Warranty? i.e. it has replaced one defective part with another similarly defective part.


4] Is there a limit to the number of trips to the Genius Bar and the same recitation of ineffective solutions: remove programs, reformat disk, remove plug ins etc?


5] At what point will it be concluded that the defect has not been repaired, and the exchange of the Covered Equipment be honored? To what extent, if any, can the Warranty be extended if a "repair" was executed within the Warranty period, yet after an lapse of three months, for example, the defect reappears? Does the Consumer have any right to Warranty repair if the repair is ineffective?


6] Based upon a review of all these threads, one may realistically conclude that there is no repair which meets Apple's criteria of "using new or refurbished parts that are the equivalent to new in performance and reliability".


7] To reiterate an earlier suggestion of mine: you can always use the machine in Safe Boot. You will lose audio and flash, but the computer will still operate.


8] As for dealing with the AppleCare Senior Advisers, while some may fail expectations, others do try to be helpful under what must be very stressful conditions. I certainly would not last 30 minutes dealing with any Customer over the telephone. Their performance is constantly scrutinized by their own Senior Staff. It must be nerve-racking. As Customers we should be meticulous in keeping records of contact with Apple Support, as well as be aware that just because we may have had a bad day, we should not unload on the Advisers. I am guilty of this as much as anyone, and my apologies to Messers. C. and K.



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Jan 15, 2016 6:52 PM in response to Lagoiski

I have been having the same issue and spent almost a year with Apple trying to get the issue resolved. Eventually they replaced my unit with a new 2015 iMac. The Apple store was never able to replicate the problem, but the genius at the store did go through the system logs and find the sleep failure and shutdown codes and then spent about 30 minutes on the phone with a senior advisor to get approval for a replacement unit.


I really wish I knew what was going on with this. It's one of the few computer issues I've not been able to solve on my own.

Jan 16, 2016 10:47 AM in response to avgeekfl

Hi all,


I am still waiting feedback from Genius Bar. They called me three days ago and they were not able to replicate the crash, I gave them some guidelines to try to mimic the problem, still waiting since then.


According with the term and condition of this forum I cannot perform polls or petitions, so I have rewriten my post deleted some hours ago.


I am very interested in:


to Robert Van Dogen: can you share your experience after receiving the first repair with only the new motherboard?

to Robert Van Dogen: is the part number of the new power unit different to the original one?

to sjkmd: can you share your experience using safe mode?


I have not seen in this forum anything about only graphic cards replacement or upgraded with the original motherboard to solve the problem.


finally, muting hyper threading or turbo boost is something to investigate as they are related to power consumption, and the graphic card will remain operative.


Kind regards,

Jan 18, 2016 1:32 PM in response to rmrbma

HI all,


Feedback from Apple, they are not able to replicate the problem, solution proposed: OsX reinstallation which of course I have already done more than 5 times from clean. They will keep working to mimic the problem. But I have gathered some important information, all the Apple Store are anti static areas and works with usb keyboard. Maybe this is something to think about. Any of you have had the problem using anti static devices or usb keyboard?


kind regards,

Jan 18, 2016 1:38 PM in response to laurent.d

Ok, so I've just picked up my iMac after being with Amsys - a UK based Apple repairer who had my iMac for 2 weeks. The repair report simply stated that there were intermittent shutdowns due to a faulty logic board which has been replaced and OSX El Capitan reinstalled. So here's waiting to see if the problem arises again.

I've had the iMac in for 2 hardware repair/checkups and 2 AppleCare Warranty sessions on software related issues in an attempt to eradicate the problem.

I'm hoping it won't return fingers crossed) :-)

Jan 19, 2016 8:12 PM in response to UKscottyGB

This is an update from my original post on this thread dated 1-8-16 at 10:48pm concerning my 27" late 2012 model imac. As a result of the latest issue, all major components within the iMac are replaced.


1-10-16

11:20am: a portable G-Drive (portable hard drive) was attached directly to the rear USB port in an attempt to perform a time machine backup. 15 minutes into the back-up, the iMac crashed.

12:45pm the G-drive was disconnected from the USB port and iMac manually powered on. Log in successful. At this time a time machine back-up was again attempted. One thing that was noted is that it took at least 10 minutes for the "preparing backup" step to complete and another 10 minutes for "calculating time remaining" to transition into the back-up actually performing. A back-up had been completed a month prior to this attempt that was much shorter in duration. No significant usage changes had been made to the iMac in the past 30 days.

1:09pm the imac crashes with "6 hours remaining" on the back-up when in previous times the backup had been performed in 10 minutes or less.


1-11-16 the area MacMan store is again contacted and the iMac brought in for observation. Hard drive tested as being in a "failing state".

1-14-16 while at the store under observation of an Apple certified-technician, the shut-down problem is replicated. At this point it is thought that the power supply is the most likely issue with the logic board also considered as a problem.

1-14-16 The following parts are replaced: main logic board (with graphics card), main power supply, and 1TB hard drive

1-19-16 The iMac service is completed and the iMac brought home. At 2:05pm the iMac with the restored parts is booted up and in good working condition. At this point a close observation will be followed and this thread updated every 2-3 weeks with updates on performance.

Jan 19, 2016 8:25 PM in response to krismanz

One omission on the last post: The power cord was also replaced


Important: everyone who experiences shutdown issues like the ones posted in this thread should contact Apple to report the problem, even if you don't have Apple Care and they can't help finance the repairs. Their main number is 1-800-275-2273. By calling, you can have your iMac's serial number registered as having the problem. Apple can then better verify the number of people experiencing the problem with this late 2012 model.

This thread has been closed by the system or the community team. You may vote for any posts you find helpful, or search the Community for additional answers.

27 iMac (2012) crashes and requires smc reset to turn on

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