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

Alright, took a few hours reading this thread from the top really hoping a solution would be somewhere.

27" 2012 (thin) iMac, purchased January 2013

Nvidia 680MX 2GB Cache

I've had the instant shutdown problem for about 6 months, I've contacted Apple Support but only to have them reference me to a store for inspection. Unfortunately for me I do not have the time to travel hours to a certified repair location only to have them discover the same issues you all have found ( or more like to have them discover nothing).

I can only speculate that unplugging our machines extending their run time is the number one clue into their problems. Wether or not the problem is directly a result of the power supply or not can not be determined as the shutdown looks to occur mostly during high graphical load. That is to say, perhaps a faulty power supply sends improper power (or just faulty electricity to be general in physics terms) to the graphics chip. Resulting in an SMC "lifesaver" shutdown to prevent damage that may or may not occur otherwise.

I've run through so many situations in my head, brainstorming a fix.

I read the earliest posts about this issue 6 months ago and thought perhaps my RAM was to blame, I had installed an additional 8 GB that came OEM in my dad's iMac, he upgraded to 32 GB when he bought his machine. Interestingly the brand of my RAM and his RAM are not the same, however the specifications are. I have no way of knowing which set truly belong to my computer anymore but I have run them separately, both resulting in sudden switch offs. The two brands are;

"ELPIDA": made in Taiwan, 4GB 2Rx8 PC3 12800S - 11 - 10 - F3, EBJ41UF8BDU5-GN F 1251GK052093 (I don't think these are serial numbers, they are the same for each stick of the same brand.)

"hynix": made in China, 4GB 2Rx8 PC3 12800S - 11 - 11 - F3, HMT351S6CFR8C-PB NA AA 1240

The only notable difference is in the SPD revisions (the number after the 11) but 10 and 11 seem to run at the same latency and with the same "math" (not an expert here). The RAM "Chips" are not identical across the two brands, that is, they are not rebranded, they are different upon visual inspection of specific molding designs and serial/product numbering. Again though, I've had crashes while running both and one or the other sets.

This is a good time to point out that my dad's computer has not had this problem, though my iMac has likely seen a 4,5,6 or so thousand more hours of use and his model is the base version purchased in spring time, 2013.

The crash occurs or has occurred in Mountain Lion, Yosemite, El Caption, Windows 7, and Windows 10 (Bootcamp)

I thought running my computer from a non-grounded outlet (old house) could be causing problematic surges so I plugged the computer into a grounded outlet (I know it's grounded, I installed it), no fix. (Additionally this has occurred in two houses from different "grids".)

I've done everything possible save removing the screen to get a look inside the machine and clean it, no avail and not hardly any dust either.

I'm definitely preaching to the choir when I say no computer should ever behave this way, even an old computer should have mechanical failures long before issues like these come up, and much later in life too, nothing close to 2-2.5 years. This error is most definitely recall worthy, I'd just like to hear from Apple that "Yes, we are aware of a possibly power related issue impacting owners of our late 2012 iMac and are studying defective models to learn the exact cause of the problem. Apple will work to rectify all models effected by means of component or model replacement and issue refunds for services previously aimed to fix the issue." Ahh, wouldn't that be nice.

I'm at the end of the thread from the end of the rope, if I can't get this fixed within the next few months, I'll likely never buy an Apple computer again.

Edit: Perhaps I shouldn't sound too grim, I've learned a lot from this thread and will be putting to use many of the techniques from contributors.

Same problem here, but I have a little bit more info that might help diagnose this issue.

I've read this whole thread for hours, so I'll try not to expand too much on my own nightmare story with unsuccessful Apple customer service since it's very similar to everyone.

My computer:

-iMac (27-inch) late 2012

-Intel Core i7-3770 CPU @ 3.40GHz

-16gb RAM

-Nvidia GTX 680mx

Had crashes for 6 months too.

My Apple Care is ending soon but it should be fine since I've reported the problem before the end of warranty.

Computer had excellent results both times when tested at the Genius Bar in the past 4 months.

Didn't had any parts replaced.

My iMac is almost only used for Bootcamp on Windows, so that is where I've seen the problem the most. (both on Win7 and Win10)

On Windows, after a crash if I go into the Event Viewer > Windows Logs > System Logs and search around the time of shutdown I can find a Critical Error from Kernel-Power, ID 41 saying "The system has rebooted without cleanly shutting down first. This error could be caused if the system stopped responding, crashed, or lost power unexpectedly."

I want to add that my computer mostly crashes when I'm playing video games or working on 3D graphic tools like Unreal Engine and Blender. I've been using those applications for years and they're essential for my job as a 3D artist.

Since my problem only happened on Windows so far, Apple blamed Windows....

So I made tests on OS Yosemite. Note that I had nothing but default applications on there since they formatted my pc when I went to the genius bar the second time. (immediately installed Win7 on it and still had the crashes so I tried Win10 and it didn't fix anything)

I installed Steam on Mac, and also installed whatever Mac compatible games I had there: Witcher 2 and Metro: Last Light.

As you can guess it crashed.

Called Apple again saying it crashes on their OS too. Apple blamed the applications.....

So I looked deeper into the issue found a similar Kernel error on Yosemite I had on Windows 10.

Here is the interesting part:

I found an error pretty much saying the application I was using was about to burn the CPU and the computer had to shutdown to prevent a nuclear explosion.

Seriously, here is the error:

"kernel: process MetroLL [366] thread 3771 caught burning CPU!; EXC_RESOURCE suppressed due to audio playback."

So I invite everyone having the issue to open the Console and search at the time of the crash if you have a similar error.

Gotta say I've lost confidence in Apple, I've been using iMac since the G3 model at the beginning of the millennium, but now I just can't accept I paid $2500 for a computer that dies after 3 years while the 2006 model lasted 7 years. On top of that, Apple just throwing the blame at other companies, or even worse blaming me because I use the computer to intensively or install "non-apple" applications on it.

So now either Apple fix this problem, or they replace my computer with a new model so I can sell it and buy myself a real PC actually worth the money.

-sigh-

Feel free to ask me any precision or more info, I got a lot more details to share if needed.

I really wish all of us to get rid of this very frustrating issue. :/

Same problem here!

iMac 27 late 2012

3.4 GHz i7

32 GB 1600 DDR3

NVIDIA GeForce GTX 680MX 2048 MB

The random shutdowns have been happening since Jan '15.

Took it to the Apple Store two times - in May 2015 & in July 2015. They were not able to "replicate" the issue, in spite of me leaving the computer for two weeks the Second time I took it to the store. After doing extensive tests they did not come up with any issues at all with the computer. They suggested replacing the logic board and power supply but did not guarantee to fix my problem! And now the issue is aggravating. My system keeps shutting down more frequently - almost every hour or so.......!!!

Reading through this discussion, it's very clear that thIs is a bad batch of iMac's! Waited for over 2 months to receive it when they came out in 2012.

Hope Apple lives up to the reputation and solve this situation.

Have the exact sam problem with my late 2012 iMac. Randomly dies, but i think it has to do with the heating. Its like every time i do something heavy like word with highres pictures i PS or something similar it dies.

Hi everybody,

I have the same problem everybody has here, same iMac 27 late 2012 shipped in February 2013. Out of the blue it started to shut down randomly about 20 days ago.

Here is what I've tried:

change the cord

change the outlet/plug

put fan at max speed

hardware test with apple tool

read the crash log

Every time it shuts down I need to unplug for about 1 minute otherwise it wont startup again.

Interestingly I've noticed that turning on "startup after automatically after power failure" make the iMac startup automatically after I unplug it for 1 minute hence the problem would be a power failure, but what's the part involved?

I really hope Apple takes some action on this shameful problem and fix it for free, it's ridiculous that a 2400 euros machine it's already broken after less than 3 years.

Ok, next update...

So I've had the iMac back for nearly 3 weeks now with no recurrence of the shut downs....that is until today :-(

It has repeated exactly the same shut down as back in Nov 2015. So a call to Apple and the outcome is to take it back to my local Apple Authorised dealer for testing and a (possible) power supply/power cable replacement.

Now this all sounds very familiar I hear you say but at the moment I suppose I have to try all the options until there is none left.

So here goes and the 5th attempt to sort my ailing iMac out.

Ill let you know how I get on.

Cheers ;-)

Mine is a late 2014 machine and its doing the same thing!

iMac (Retina 5K, 27-inch, Late 2014) 15,1

3.5GHz Intel Core i5 with 8GB of stock memory

AMD Radeon R9 M290X Graphics

El Capitan 10.11.3

I dont have anything attached to the machine and I am using all stock programs. I used it 90% of time for just light surfing using Safari. Viewing photos is my other "work". I am not editing mind you, just viewing them using Preview.

I bought the machine around Feb 2015. I didnt start to use it till June 2015 as I was moving house. Problem started in Jan 2016. Since then it has happened for about 7 to 8 times. Thrice, when it happened I was looking thru a bunch of photos. Twice it died when it was in sleep mode. Once I was surfing using Safari. It can happen a week apart or few minutes after rebooting (yes have to reset SMC first each time). I dont think its dirty or its a heat issue. It doesnt feel hot to me, not even warm.

I have not got Apple to replace anything. Just Chat with them doing some resets which is obviously useless. My warranty is expiring in 9 days LOL.

My first and last iMac. 😟

Thanks UKscottyGB for sharing,

can you tell us what they did in the first repairing session?

HI,

the iMac was kept for a week to run tests. After chatting with the engineer he reported that the main logic board had developed a fault, (he did not specify what the fault was), as a result the board was replaced with a new one. The Fusion Drive was wiped clean & the OS was reinstalled. The iMac has shut down again twice today without warning so the conclusion must be that the logic board as not causing the problem. I'm hoping to take it not my local Apple dealer this week to run tests on the power supply + cable. I'll or you know how I get on.

Well, it's ridiculous for Apple to handle these kind of malfunctions in such poor and dodgy way. I bought my first Imac in 2006 and is still running even if it had the superdrive broken twice and a stain on the monitor, all the time the machine has been repaired for free. Now these machines are broken after 1 or 2 years and Apple does not care. Shame on you Apple!

UkscottyGB, please tell us how you get on with next round at the genuses, I heard that it might be a faulty Power Supply board, the capacitors in particular. Hope you solve your problem!

Hello everyone out there.

- I love ( and hate ) this thread and i'm hit a 100% with this problem.
- Please stop local diagnosing. The core to this problem is a malfunctining hardware component ( probaply a malproduced capacitor

on the PSU ), but Apple knows..... Come one, please tell us, so we need to know, what is to be replaced????????
- Servicecenters can't replicate the problem. WHAAAAAAAAAAT..... I can do it every day and it is very consistent. I just have to

leave it turned on and it happens.
- Bootcamp or not. Problem is totally the same!!!!!
- A non-detectable heat issue that is actually logged!!!!!!!!!!!! Hardware problem!!!!!!!!!!!!!!!!!! Apple know's exactlyhow to interpt logs..... and how not to!!!!! I don't think this is a controlled shutdown ( or whatever one would call it ), due to heat!

I have to pull the plug physically for 10+ minutes... otherwise I can't turn the computer on again.
- Apple? Please respond!!!!!!!!!!!!!!!!!!!!!!!!!! Tell us what to do?

I have a lot more to say about this issue, but I'll keep it short. Apple needs to respond!!

APPLE KNOWS TOTALLY WHAT THE PROBLEM IS!!!!!. When did silence become the order of support?

... PS

So I got my motherboard replaced 2 weeks ago by apple, the problems just came back, PC crashed same Kernel error. I'll go back to apple store sometime soon. -__-

I've got my iMac back with a new power supply board fitted & replacement power cable. It's been running for 3 days now & has not shut down once. I had it repaired at my local Apple Authorised Service Dealer (not at Apple Genius), who have been gr8! They ran hardware diagnostic tests on the repaired iMac & could not find any faults. I have to be fair & say that Apple have repaired the iMac each time it's developed the (same) fault but my confidence with this particular iMac running fault-free is low.

I will keep you updated if the fault reappears or indeed if it completely disappears.

This thread has been invaluable. I have this same late 2012 model. Bought second hand in 2013. Thank you everyone for your advice and tips. I took my Mac to the Apple Store last week. Following advice from this thread I made sure my Mac had been running all day before I took it in and I had a diary of all the times it shut down - last time was one hour before my appointment. It actually shut down during a diagnostic at the Genius Bar. With no arguments, no warranty and no Apple Care they replaced the logic board (graphics card is integrated on this board the Genius informed me) and I paid for a new hard drive which showed a fault. We agreed the HD fault was a separate issue. Because of UK consumer law I did not have to pay for the logic board and labour. I felt the service was excellent and was really pleased.

That was the good news. The bad news is that the same fault happened again last night – twice – after having been on for three days mostly in sleep mode. Going back in on Saturday to discuss it again, with my new diary entries of shut downs/power-offs.

Robert van Dongen has replacing the power unit done the trick for you?