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

For what it is worth my late 2012 imac with a non fusion disk has just started to have exactly the same problem. Come on Apple at least look into this and come up with a chargeable fix at worst, your processes missed this manufacturing defect with the late 2012 imac.

Hi everyone,

This morning, I was watching videos when I had to go to the kitchen check some food. When I came back, my imac 27 (2012) was shut off! I was wondering what happened then. So I tried to switch on with the power button in the back, but it didn't work at all. I felt very stressed at this moment because my applecare is over since March, and the PSU had been replaced on february, so I guess it's not linked with PSU. Anyway, I managed to reboot the Mac, by unplugging the power cord from the wall, waiting a few seconds, and plug it again. Then the power button worked again, and I was able to use the computer again. I won't switch it off now, because I'm afraid the problem occurs again. So I only use the sleep mode.
What is the cause of this problem? Planned obsolescence?

Your issue went away when you stopped using Safari? That's weird because I don't use and never have used Safari yet I still have random shut-downs.

iMac (Retina 5K, 27-inch, Mid 2015)

3.3 GHz Intel Core i5

8 GB 1600 MHz DDR3

AMD Radeon R9 M290 2048 MB

THE RANDOM SHUTDOWN PROBLEM STARTED HAPPENING TO ME ABOUT A WEEK AFTER MY 1 YEAR WARRANTY. I DID NOT GET APPLE CARE BECAUSE I DID'NT EXPECT TO HAVE ANY REAL PROBLEMS WITH THIS COMPUTER. MY FIRST TIME EXPERIENCE IS VERY SIMILAR TO MANY OTHERS FROM THIS THREAD. IT SHUT DOWN RANDOMLY AND I COULD NOT TURN IT BACK ON RIGHT AWAY. AFTER UNPLUGGING IT, WAITING A WHILE AND PLUGGING IT BACK IN, IT TURNED ON. HOWEVER THE SAME PROBLEM OCCURRED NO LESS THAN AN HOUR LATER. I DID SOME RESEARCH AND FOUND THAT "PREVIOUS SHUTDOWN CAUSE: 0" MEANS THAT THERE WAS A POWER DISRUPTION. I BROUGHT MY COMPUTER TO THE APPLE STORE ON THE UPPER WEST SIDE OF MANHATTAN AND TOLD THE GENUIS THAT IT WAS PROBABLY A POWER SUPPLY PROBLEM GIVEN THE SYSTEM LOG CODE. HE SOUNDED LIKE HE AGREED WITH ME. AFTER A FEW DAYS WITH THEM, THEY DIAGNOSED THE PROBLEM TO BE WITH THE LOGIC BOARD. I PAID $721 BUCKS TO REPLACE THE LOGIC BOARD. I USED IT ON JUNE 21ST (THE DAY I GOT IT BACK) WITH NO PROBLEM. THIS MORNING ON THE 22ND, I EXPERIENCED THE SAME RANDOM SHUTDOWN. I UNPLUGGED IT FOR ABOUT 10 MINUTES AND TURNED IT BACK ON. I LEFT IT ON FOR OVER 3 HOURS ON SLEEP MODE, CAME BACK AND I HAVE BEEN ON IT FOR ABOUT 6 TO 7 HOURS.

TO ANYBODY HERE, IF THERE WAS A PROBLEM WITH THE LOGIC BOARD WHEN WE EXPERIENCED THESE RANDOM SHUTDOWNS, THEN WHY DOES THE SYSTEM LOG INDICATE THAT THE PROBLEM HAD TO DO WITH A (POWER DISRUPTION ISSUE) AND NOT ANYTHING TO DO WITH THE LOGIC BOARD?

WHY HAVE SO MANY OF OUR CASES BEEN DIAGNOSED AS LOGIC BOARD PROBLEMS FIRST WHEN THE MAJORITY OF THE TIME, THIS ISSUE HAS TO DO A POWER PROBLEM?!?!?!?!?!??!?!?!?!??!?!?!?

Wanted to follow up on this.

I first brought my iMac (27-inch, Late 2012) 3.4 GHz Intel Core i7 NVIDIA GeForce GTX 680MX 2048 MB 1 TB Fusion into Apple for repair last month, they kept it for a week and said it was the SSD failing which is part of my fusion drive, and charged me $500 plus to fix it. Pricey, but problem solved, right? No.

I got it back, problem persisted. I took it back in.

Very thankful that on my second visit I got a knowledgeable and helpful genius who knew right away that the SSD was a misdiagnosis of the problem. He refunded my $500 and told me that he was almost certain it was a power supply issue. He also repaired that for free since they wasted my time the first go around.

I've had the computer back for about a week and so far so good (though, only time will tell). This is what I've concluded:

This is a HARDWARE issue. I refuse to believe that we are all using some special combination of software that could be causing this issue when we all have the exact same model of iMac.

My advice is take your computer into Apple, show them this thread and that it isn't an isolated issue. Have them repair your power supply first, which is the cheapest of the repairs I've seen (around $150 at my Apple store).

I assume the log entries are just showing where the problem occurs and not why the problem happens. In my case its a software issue but I have the exact same problem of what you describe. Just when I stop using Safari I dont have it anymore. It seems to work just for me but you can see the variety of the problems is huge and in the end its always that random shutdown problem.

Another one here!

iMac (27-inch, Late 2012)

3,2 GHz Intel Core i5

NVIDIA GeForce GTX 680MX 2048 MB

After reading the 21 pages of this post I've no solution yet 😕

I hope anyone can find a solution. I think I'll try to change the power supply by a non-original replacement.

All I can tell you is what helped me and solved it until today.

I uninstalled Anti Virus Software and Steam. In my case it was Safari which was the problem. When I switched to Firefox I had no problem at all.

On my side it was a Software issue but it seems there are lots of causes for this behavior.

Hi there! Just a little update that works by the moment for me.

My shutdown problems started on June, I live in Barcelona so in June is very hot indeed. My office is on a attic where is so warm. I suspected that the shutdown problems where from that but I've installed Mac Fans Control and I thought that will solve my problem.

After few days trying some methods (installing a clean SO in another partition, replacing RAM modules and so on) I moved my computer to the bottom flat in my office. The temperature was fall (in the near processor sensor) from 51/58º to 42/44º... Since 2 days here with the iMac running a lot of applications the problem seems to be solved.

I hope it helps someone.

Just an update. After being promised that Apple was going to replace the iMac, three weeks later, still have not received the product.

Just an update from me - after updating the OS its getting better. My Safari Bookmarks are not mixed anymore, this is solved. But from time to time I still have that shutdowns... I will wait until sierra is out (no beta) and hope that will solve it once and for all...

Oddly, I've noticed that occasionally (perhaps one in every 10 or so events), I am able to press the power button and the machine will wake from hibernate. I'll get the series of dark grey rectangles across the screen that sequentially lighten and the machine will restore to its previous state.

Why (or how) an iMac is going into hibernation, I have no idea. I always count it as a win if I can recover from a hibernate. unfortunately it does mean I'll be due another event somewhat soon.