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

Dec 14, 2015 6:56 AM in response to paul_ngc

Hi Paul_ngc,



Still waiting. At least we have caught Apple's attention to this matter. Fortunately, the Apple representative who fixed the machine twice documented everything, that is, the replacement of the Logic Board first, and later the power supply. I e-mailed both reports to Technical Support, and pointed out the futility of fixing this machine. All they can do is temporary fixes, the machine passes all tests, so I am sure the problem will arise again. Clearly a defective model. Therefore the only solution is the recall of that model and replacement with one that actually works as intended.

Dec 16, 2015 11:22 AM in response to Lagoiski

I've had the same issue since February of this year after 2 years of owning this machine (late 2012 model). Made a Genius Bar appointment in October and they were unable to replicate the issue after keeping it for several days. Also, the issue did not show up on any logs even when I gave them the time/date of occurrence. This is utterly frustrating and I believe a recall is warranted for this machine. Specs for my iMac are below.


3.4GHz Quad-core Intel Core i7, Turbo Boost up to 3.9GHz

8GB 1600MHz DDR3 SDRAM - 2x4GB

1TB Fusion Drive

NVIDIA GeForce GTX 680MX 2GB GDDR5

Dec 18, 2015 2:05 PM in response to Joe5000

Just adding my voice: 27" iMac, late 2012, same intermittent power down issue, repair shop has looked at it twice and can't find anything wrong, passes all diagnostics. It seems to occur more frequently when anything is plugged into a USB port, but that might be coincidental.


Definitely hoping for a recall or a fix!


Thanks for your efforts


Jan-Peter

Dec 21, 2015 12:47 PM in response to Lagoiski

Update: Took the iMac into the Genius Bar. We weren't able to get the problem to replicate there however they kept the unit for the week and performed a replacement of the logic board. Considering that others in this thread have had the same replacement performed without relief of the symptoms I'm pretty skeptical that the issue is resolved, however I'm trying to be as patient as possible and let Apple figure this one out.


Just out of curiosity has anyone considered a replacement of the video card? That seems to be another constant for all of us thus far in this problem.

Dec 22, 2015 11:35 AM in response to Redbridge13

Apple has requested that I send them my ailing late 2012 27" iMac, which I have done. Their engineers are going to tear my machine "apart," (in techspeak) to try to isolate the problem/s. Hopefully, they will find the answer. They asked me questions for a half-hour and I reiterated all of the steps I had taken so far, which I had posted here. I had not yet replaced the power supply, logic board or video-card. Mine starting acting up after two years - doesn't this seem to point to some failing hardware? I am more than satisfied with their response and very happy that they are really looking into this.It is just a matter of time now...

Dec 22, 2015 12:22 PM in response to mikestan56

So even after having the logic board replaced, the problem resurfaced yesterday. After talking again with Apple we decided to try wiping the computer and booting from an external drive. Once I did that the problem again resurfaced so I have another phone call scheduled for today. The most recent representative that I spoke with was incredibly helpful and has a theory on what may be causing this. Also as an FYI I learned yesterday that the video card is built into the logic board, so a replacement of one usually means a replacement of both. Therefore it seems like that isn't our problem either. I'll keep everyone posted. I definitely urge everyone here to touch base with Apple to verify this is a wide ranging problem with this model.

Jan 1, 2016 6:40 PM in response to prankster506

Good news: Apple has decided to replace my iMac for a 2015 model. I couldn't expect less than that from this great company. I am satisfied with the speed of their response. It will be a couple of weeks or more before I get it, since it's coming from the US to the Caribbean. So far I would like to thanks *****, ******and specially ****** for their due diligence.


<Emails Edited by Host>

Dec 22, 2015 12:51 PM in response to Redbridge13

Just a quick update: my computer has not shut itself down for about a month now, since the power unit was replaced. Logic board replacement did not solve the problem either. Still can't tell if problem is gone for good, but one month of really intensive usage without shutdowns looks promising. I even installed Windows 10 just to let my son play Star Wars Battlefront on my downtime, thus giving the GPU a really hard time.

This has to be at least related with the power unit, if not caused by it.

Dec 23, 2015 5:36 AM in response to Joe5000

That's great news! I've had mine back for nearly 3 weeks now after being checked. The problem could not be found during the week it as with my locks Apple dealer and it has not resurfaced since then. I left it on 24/7 for the first week back running Crashplan, backing up my files remotely. It has been used intensively since but at present is behaving itself. However my confidence in this iMac continuing to operate as normal is low, so iI will post back with any updates. Have a good Christmas everyone

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

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