iMac (Retina 5K, 27-inch, Late 2015) Randomly Restarts Without Errors

The first one senior advisor I talked to called the service center and told them to do more diagnostics and check the power supply. It was that advisor's last day so he sent me to another advisor who, to me, didn't respond about the logic board when I asked her to tell the service place that they should look at that too. However when I took the computer back the service guy said he was going to replace the logic board because he didn't think it was the power supply. I had brought all kinds of evidence of others getting new logic boards in case they weren't going to do that but it turned out not to be necessary. I am pretty sure apple knows it's a hardware issue not software so get to a senior person and explain about the apple stores and other service places replacing the logic boards in these models and why shouldn't you get that fix too. I don't know if my second advisor told the service place to replace it or not but it seemed funny that that was the first thing they said they would do when I went back the second time. I am in rural Wyoming so I hope you can get this fix too. i just think that if you keep calling or emailing about others who reported on this board that they got a logic board replacement you ought to get one too.

Hi!

I'd make an appointment to speak with someone at your nearest Apple Genius bar. Considering your location, it's possible they'll be run diagnostics remotely? Another option might be to ship the machine directly to them.

After running more substantial tests, they realized that the problem was in a faulty video card, hence the logic board replacement.

Jason

Hmmm––so the local guys ran all the Apple diagnostics they could think of (supposedly) and couldn't find a reason to justify a replacement––they were able to keep apps running longer than I was (close to 8 hours) before getting the -128 shutdown error documented in the Console.

So for now, not sure what to do, and if I can get the logic board/card replaced. I shared this topic with them and they looked at it, however, their diagnostics run over 2 days yielded nothing in their minds that can justify to Apple replacing it.

So not sure what to do at this stage. I have the computer now, because I need it for projects, but it does not appear this issue is resolved.

The solution is simple for Apple. Just swap out these defective machines for us. Save your techs time, save us money and make everyone happy. If they can pay out $500 million for lousy Ebooks they can send us new machines.

So i got my iMac back with a new logic board. Sort of afraid to turn it on. Can anyone who got new logic boards confirm that since then, they've had no restarts? That the logic board was the fix? Thanks for all the support I've found on this discussion.

So the new logic board has 10.11.1 on it and now i have to do the backups. If I update to 10.11.5 with combo updater do you think i will get more restarts; should i stay with 10.11.1?. My last backup on my TC was 10.11.5 but that backup was done during all the restarts. I can't face the restart issue again! Thanks again for your comments.

To be 100% sure, I wouldn't touch 10.11.5. That was the issue for mine (no logic board replaced, but mine just shut to black - no restarts) but others have had no issue it seems. I just wouldn't be touching it. I'm almost contemplating not moving to macOS Sierra when it comes also, as I'd rather not take any risks and have to do another data reinstall or encounter new problems when that (and its new file system) comes along.

I am now on my 3rd Supervisor as #2 stopped responding to my e-mails. The e-mails were all cordial - just asking what is the next step, etc. I do all my ranting and raving here.

Now they have me signing in under a new "user" to see if it a software issue. Another "user" runs off different software settings so if it still restarts it is a Hardware issue more than likely. I asked for a new Logic Board but they can't just start swapping out parts. The Engineers still don't know what is happening.

The funny thing is I sent the thread to the new Supervisor and he says the random restarts is not a known issue to Apple - that we are all a super, super minority and this issue is rare. Anytime there is an update something screwy happens to a fraction of the machines. Sounds like Denial to me. Can you say E-books.

Surprise Surprise , 4 days later, and boom, restart.

Don't have the energy to argue with apple support tonight so will contact them on monday.

Im slowly starting to give up, this is becoming a f&*%$ng joke.

I feel your frustration here.

Just had a chat with AppleCare on friday myself. The machine keeps restarting and even though I refer to this thread they simply wave it off with "Whatever trouble you may have, you will always find users with similar problems. That however does not mean that there's an issue with the hardware."

Nice.

I'm contemplating just leaving the iMac with the retailer during the holidays. That will give them 14 days to solve things. Doubt they will be able to, though. Seems like they are grasping at straws at the moment.

-KJ

Dealing with Apple has been the most frustrating thing for me thus far. All the service reps are cordial and seem to be reading the same 3X5 card:

"We understand your frustration, I would be frustrated too."

"Unfortunately I can't authorize an exchange, no one here can either. Apple just does not do that."

"This is not a known issue with the 5K Retina Machine - you are the first person I have talked to with this issue."

The head of customer service said he didn't even want to see the thread as it serves no point - another scripted response:

"We are trying to focus on your own problem and the thread is about other people's problems. So me reading it will not help you."

So asinine it is maddening.

I can't even get authorization to take mine in even though the logs I sent clearly show some kind of error. Besides, it seems pointless to leave it with them anyway as the previous poster had left it with Apple for 2 weeks and it just randomly restarted.

How frustrating! I'm sorry this has been so difficult. Is it possible for you to just make a Genius appointment in person? If you're under warranty (you should be, we all seem to have bought these within the past 6 months), they should replace the logic board for free.

All my troubles started with an update from 10.11.3 to 10.11.4. Going back to 10.11.3 via my TC backup didn't help nor did going up to 10.11.5 once the "damage," whatever it is, was done by 10.11.4. Now I have a new logic board and 10.11.5 on a totally clean hard drive and so far so good.