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

It cost £85 GBP including tax. Which is a lot less than a new logic board at around £500GBP so I'm hoping it's done the trick. I have 90 days warranty on the new part so I'll be putting the machine through it's paces intensively until then. I will update if it happens again.

Thank you for the update and do please keep us posted. It's quite bizarre to me that they would replace the logic board on mine, but not suspect the power supply, especially considering the evidence and the price difference. It's also strange to me that this issue seemed to crop up in about the same time frame for many of us, but at this point I'll take anything in the name of progress.

I agree it would make more sense to replace the power supply first. The reason they look at the logic board is because the SMC chip is on there which of course needs re-setting each time it unexpectedly shuts down. When I first took my computer in the engineer suspected the SMC chip and suggested that the logic board might need replacing. It was only when they were able to see the machine shutting down on their bench that they looked at the logs and then the power supply. It's probably too soon to say if it's been completely fixed but it's promising at the moment.

I will be getting mine back early next week with a new logic board fitted, so it'll be interesting to see if the problem is fixed. After reading other people's posts I guess I may be posting again in the future with this recurring problem. At least Apple are doing something about it, however I just want a fully operational iMac back!

Same problem here (27" iMac late 2012 crashing) as everyone In this thread. I took mine into the local Apple "Mac Man" store for service and was charged $79.13 for some extended diagnostics and an overnight stress test. No crashing issues could be replicated so I was sent home. Thought it might be software issue but they were unsure. This was on 12/7/15. For three weeks no issues arose while using only safari and nothing else. On 1/1/16 the problems returned. I've kept a precise log of what's occurred thus far:

1-1-16 1:45pm... iPad connected DIRECTLY to rear USB port (using Apple cord) in rear of machine to perform iTunes backup. Backup completed successfully and iPad ejected properly. A second different iPad connected. At this point the iMac immediately crashed (powered off).

1:55pm after removing the cord, iMac powered on. Upon log in, computer crashed again. Decided to wait a couple hours before attempting power on again.

3:40pm iMac powered on. This time log in successful and computer functioning with Safari. Did not attempt to connect second iPad again.

6:20pm iPhone connected for iTunes back-up and update. During update, iMac crashes & powers off.

6:55pm iMac powered on. Upon log in crashes again.

7:25pm iMac powered on. Log in successful and computer remains on. Did not attempt to connect iPhone again.

1-2-16 safari & photoshop used to edit 3-4 jpeg photos. No issues.

1-3-16 safari used no issues. Seagate portable hard drive attached directly to rear USB port to transfer several jpeg file photos. No issues.

1-3-16-

1-7-16 Safari only usage. No issues. Computer remains in sleep mode after 15 minutes & powers on next day when pressing space bar. Four days, no issues.

1-8-16 6:33pm a Delkin photo card reader is attached directly to the rear USB port. Photos (three total RAW files from a Nikon D800 camera) uploaded. Upon appearing on screen in the apple photo window the iMac crashes (Powers off).

6:58pm Delkin card reader removed. iMac powered on. Upon log in crashes again.

7:30pm iMac powered on. Log in successful. Safari used no issues for remainder of day. No attempt to attach card reader again.

Someone had had asked about service & repair charges. Here are my quotes for Wisconsin Mac Man store quoted 12/7/15:

Power Supply (part) $103.51

Logic Board (part) $799.00

Labor rate per hour $75.00

Diagnostic charge $75.00

HI all.

I have had the same problem for months. Today I have decided finally to leave my iMac in Genius Bar ( iMac 13,2 16 Gb Nvidia 680Mx, 128 Gb SSD, 1Tb HDD ). These are the tests carried out and the evidences I have collected:

Tests:

1) problem happens with fusion drive or without

2) with mountain lion, Maverick, Yosemite, El Capitan (Clean installation -> HDD & SSD formated)

3) with or without USB devices

4) with of without wifi

5) hardware test Ok

6) stress test Ok: CPU 4 cores 8 threads by terminal command and graphic card by specific Nvidia stress programme.

7) temperatures ok, below 95C under stress conditions

8) no kernel panic dumps

9) no grey screen during shutdown

10) SMC and NVRAM reset (SMC reset requires more that 5 min to go live)

11) SAT available.

12) Nothing repeatible at first look in the log file after every crash.

Evidences:

1) happens during OS X installation.

2) with only Safary

3) with gaming and photo edition programmes

4) running on a single programme or while changing from one to another.

5) time with no problems depends on unplugged time

I will be back when I have more information from Genius Bar.

kind regards,

Same problem. Three times to Apple Genius staff. Not fun shlepping this 27" iMac back and forth. Am on my third Apple Senior Adviser now.

I'll tell you what DOES work: boot in Safe Boot [Turn on power while holding down SHIFT]. Of course you lose a lot of video and audio. But it will work. Acts somewhat funky.

Now, why would I have to discover this myself? Why wouldn't Apple at some level suggest this as a workaround? Perhaps because it clearly narrows the problem. Why would Apple want customers to ask logically: Hey, it works in Safe Boot, but not normal boot? Can't you use that information to find a solution?

Too simple.

It's hard to imagine that Apple does not know about this issue.

I suspect that they will just stall all of us until the three year Apple Care Warranty expires, and that will be an end to it. Apparently they decided that it's better to waste the resources of Apple Genius Staff and Senior Advisers on this problem, than ship a replacement and honorable honor the Warranty. In business terms, the Apple Genius staff are fixed costs, as well as the Senior Advisers. So it costs Apple nothing to expend time on this useless pursuit.

On the other hand, to replace the iMacs DOES cost real money in terms of product shipped and not paid for. In addition, a cynical decision was made that a certain percentage of unhappy customers will purchase a new Apple machine, regardless of their experience.

And that's where we are. The Senior Advisers seem to be unaware of this thread, and there is a grand and laughable game of pretend: Apple pretends that they are honoring the Warranty, and you all pretend that you understand Apple's sincerity here.

These are defective computers, and all of us should start writing the Consumer Protection departments of your State's Attorney General office. Otherwise, you will just give up out of frustration.

One last thought, my warranty expires end of this month. I started complaining about this beginning in March. Although the Apple Senior Advisers assure me that they will still honor the warranty even after it expires, because I brought up the problem within the warranty period, does anyone really believe that as soon was the Warranty has expired, no one a Apple Care will even speak with you on the phone unless you start paying for service? You will be told that Apple Senior Advisers are not authorized to extend Warranties. After all a Warranty is a specific, written legal promise.

Well, I hope that helps this discussion. Remember: try Safe Boot for functionality, although limited. For some it may be OK.

I've had this issue from July till December. The first thing tried was a logic board replacement but it didn't do the trick. The second attempt was the power unite replacement. Outcome: not a single sudden shutdown for more than two months, and counting.

Robert how's things going with your machine after this replacement? After reading and watching this thread for some time I feel like we all need to come together and file something like mentioned before maybe with local Attn Gen or something this is a huge issue with so many people and nothing is being done about it.

I agree with you completely. I tried to post a link to a site with a call to action on it but Apple took it down. I understand they want to ignore the problem—but c'mon, anything with an Apple logo on it SHOULD be a symbol of quality, and as a faithful devotee of Apple (growing up we had Macs dating back to the Apple IIe) it really makes me second guess them if they fail to do the right thing now.

I am convinced that the error reporting system, the logs and files which Apple will request from you, the ACCS files, are worthless. Not only do they fail to point to the error, I have also found that the so-called Engineers do not come up with realistic solutions. So far, I have disabled a dozen programs, and half dozen plug-ins, disconnected my LaCie drive etc - - all based upon what the Engineers saw in the logs. None of those fixes worked. This is a case of throwing sh-t on the wall to see if it sticks. The logs, which you can see in the Console module, are simply unreliable. After all, wouldn't all this have been fixed long ago if the logs WERE accurate? The system logs are giving false readings.

When I brought my iMac to the Geniuses the first time, they reformatted my hard drive, and load fresh with Yosemite. Now, I am being advised by the third Senior Adviser I am dealing with to again bring it in to have the hard drive reformatted again. That tells me that they have no clue, and will not honor the Warranty. In effect, as many of you know by now, the Apple Care Warranty works like this: you get free Tech Support OVER the phone, after you come up with no solution from the Geniuses in the Apple Store. You will now act as a free Tech Support Assistant and perform all sorts of fixes on your iMac. There is no limit to the amount of time and inconvenience you will have to undergo, and there is no end point, at which Apple will replace your defective iMacs. You will spend hours browsing sites like this, trying to come up with technical explanations and so forth. Unlimited input from your part, and very limited and ineffective help from Apple. That's what your Apple Care Warranty really means.

In the real world, a billion dollar company would replace your purchase, and pretend at least to care about all the hours you have devoted to this and your frustration. Not at Apple.

For those of use old enough to remember, I recall similar frustration dealing with Windows 3.1 and the Files and Buffer settings. At that time Microsoft made an inferior O/S and we were all stuck with it. No apologies. That's how Apple captured market share in the end.

But now, the Apple strategy is to wear you out: make three trips to the Genius Bar, then out of frustration you will speak with a Senior Advisor. And after the Engineers throw cr-p on the wall with guesses, once again they will suggest that you bring it back to the Genius Bar where THIS TIME it will go to a special Apple Depot where they will REALLY get serious and fix these defective iMacs.

As I mentioned earlier, a workaround is to do a Safe Boot: power on while pressing SHIFT at the same time.

So they replaced with the same power unit, which will start to malfunction in two years?😀

Sjkmd your right for sure. I've worked in IT for awhile and this problem could be the worst one I've ever seen as you can't pin point what's actually causing it. I really feel for the people who need the computers for work related things like photographers, video editors, etc......I would have thrown this machine out the window months ago but like everyone here we try to remain patient but I'm loosing mine now. I was so reluctant to get this machine for this reason due to the fact it was self contained and if something needed work or troubleshooting hardware based it would be tough to get to and here we are. Brutal! My machine is not under AC any longer and after reading all these post I will not take it in until we find something credible to replace or fix. Might actually take mine and stand outside the Apple Store in Providence RI this coming weekend and demonstrate why not to purchase anything in the Imac series even if your like most people here and actually love the machine when it preforms right....I'll open PS and Lightroom and give it 5-10 minutes and let them see the screen go black without any real reason on a well maintained and immaculate machine 🙂 and say this will be you in 2 years.....anyone local want to join me?

Another one with same problem. 😟

Hope a upgraded power supply will be the fix.

Imac 27" Late 2012

Core i5 2.9

16 GB 1600MHz Ram

Nvidia Geforce GTX 660 512 VRam

Bought April 2013

First problems Dec 2015

Hey guys.

Sorry for my bed english.

Anyone has detected same problem using UPS? Sometimes the shutdown was generating by electronic component due to power supply problems.