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

Thanks, Michael M, for posting your firmware versions. We're running the same firmware, so it looks like changing the firmware isn't going to work for me. I guess I'll be getting my logic board replaced.

Despite it only occurring perhaps once a week, though multiple times repeatedly that day, my iMac still shuts itself to black when it likes. Finally taken into an Apple Authorised Service Provider to get it looked at. They said they'd be looking at it tomorrow and if it's what I'm saying, and all of you are saying, they'll be replacing the Logic Board. Strange that a software issue can then become a hardware one due to a minor software update. Will definitely be waiting things out a lot more before doing ANY upgrades in the future. macOS Sierra had better be rock solid for me to even consider. No way will I be upgrading to that until I've searched these forums for issues. Sad but true.

So far 5 days now and after logic board replacement computer has not randomly restarted. The tech who replaced my logic board says it is bad Firmware which makes it a software issue of sorts but the Firmware is software embedded in the computer BIOS that can't be erased. So the only solution is swapping out the Logic Board to correct it. He says the OS updates trigger something odd in certain late 2015 5K machines. From what I understand the Firmware is a bridge between the software and hardware so it is is wonky things like the random restarts will happen.

Apple replaced my refurbished unit with a NEW unit same specs; never did find the issue. I'm a happy customer now.

Since logic board was replaced on 6/23/16 no restarts! I have same firmware version: IM171.0105.B08. Hope that with this probable resolution, others can get their machines fixed.

Hey folks,

My iMac 5k is in for a logic board replacement! WOOHOO!

The plot thickens!

While on vacation, I was called by a super senior Apple rep who admitted that Apple's Engineers have no idea why this problem is happening. They acknowledge that changing out the logic board seems to fix the problem, but they're more concerned with what is causing the logic boards to go bad in the first place.

She wanted me to conduct a "deep, encrypted diagnostic" and send it to Apple, as this type of diagnostic would give them more info. The problem was that, while encrypted, it would contain any personal info traces on my machine dating back to when I first started using it.

The engineers then, in her words, after looking at this diagnostic, "might agree to" send me a brand new iMac 5k and use mine for testing.

This wasn't good enough for me. I told her I would consider running the diagnostic if I had time, but that the idea of my personal info being sent out like that was uncomfortable to me.

If Apple wants these machines to test and discover why this happens, they should just offer us all new iMac 5ks and test the faulty machines. Period.

I took my iMac 5k in for the logic board replacement on Tuesday––I should have the iMac back either late this afternoon (4-5pm MT) or Monday-Tuesday next week.

As others have done, I will continue to provide updates post operation on my iMac 5k so that this topic is kept alive and any who have this problem will continue to have leverage with Apple by referencing this topic.

Hi folks

I'm delighted for those with new motherboards and Apple's acknowledgement of problems - sadly that's not the experience I'm having in the UK.

My machine went into the Genius Bar - passed initial stress testing. I agreed to let them wipe the machine and rerun the tests on a clean install, again nothing showed up.

Despite having the opportunity to have the machine 'on test' e.g. logged in but idle for 2 weeks to spot any restarts (as I'm on holiday) I was told that they don't have space to leave machines plugged in for extended periods, that these message boards are specifically not referenced by the support technicians and that I'd be getting my machine back without a logic board replacement until/unless I can reproduce the problem again (presumably to their satisfaction, no idea what that will entail??).

I was definitely not happy with that position but will reluctantly leave my machine logged in with *no* other software on it until I get a restart, to prove it's not any software or data I've installed.

If anyone has any pointers on how to attract the attention of the Apple Outreach folks referred to above, or to the technical issue that's now seemingly acknowledged, I'd love to hear it (by private message if you don't want to broadcast to the world).

Apart from that I'll be trying to ramp up the pressure on Apple when I collect the machine, and pointing out that they need to be a little more conciliatory in their approach as currently the feeling I get is that I'm being seen as a nuisance if not an outright liar, rather than a technically capable user who's done his research and has a genuine (though hard to reproduce) issue.

Given the thousands I've spent on Apple gear over the years, it's unlikely to prevent me buying in future, but it's a far cry from the positive (and human!) response others in this thread seem to be (eventually) getting.

Mike

I just called a local independent repair spot and they explained they can't acquire the new logic boards for late 2015 iMacs and don't believe anyone else can either. This is really dissapointing if true as even though my machine is still under warranty I can't have it sitting with Apple for weeks I'd rather pay the cost of repair (not Apples ridiculous rates) and be done with it.

I can find all kinds of late 2014 - mid 2015 logic boards for a couple hundred bucks, anyone have any insight on the late 2015 boards is there a difference, or where I can acquire one?

"The Squeaky wheel gets the oil," as we say over here in the US. Keep posting and complaining - call Apple as much as possible. Eventually you will land a Supervisor who will OK the Logic Board replacement.

Mine was replaced on July 27th and no random restarts since then - 9 days so far - I think it is in the clear. As the last person noted Apple does not know the reason for the restarts but the repair techs have seen bad Firmware in the past and to them this seems to be the issue. Since the Bios is located on the Mother Board (Logic Board) replacing that part solves the issue.

I would have gladly sold them my machine for $2,200 but Apple did not want to buy it back to run test on it. Now I see they want some bad machines to dissect - they are getting smart.

I am very pleased with Apple for sending a tech to my house to replace my Logic Board. Five star service in my book now.

mrdgvb1 is right––we've either had our logic boards replaced or have our computers in the shop having that done right now––but that is ONLY after bothering Apple for over two months and not allowing them to sweep the problem under the rug.

There were people with this problem even earlier who got their logic boards replaced a month or a couple weeks before us, as documented in this thread, and they kept telling us to "hang in there." So that's what I'm saying to those still battling Apple right now. Keep on them, you will get your machine fixed.

If your machine is under warranty, don't go pay for this repair yourself––demand Apple do the right thing, and when on the call with Apple, always mention "the logic board is the problem." Never admit that it could be something like software. Be willing to go through the steps they deem necessary to reach that end, but don't relent on the logic board issue.

I had to hound my senior advisor with "the logic board is at fault" for weeks until he relented.

It's not a fun situation to be in, however, it is the only path available right now unless Apple goes public and creates a widespread, voluntary but encouraged free recall/repair of machines. They're going to treat each issue, no matter how similar or exact it is, as an isolated problem.

I have not been so lucky, I can't seem to find a supervisor/Senior Advisor that has been able to approve replacing the logic board. I have been bugging Apple since Mid May and seem to be banging my head against a break wall and getting no where fast. Very frustrated. Would anyone that has had their logic board replaced be willing to let us know who they worked through as it might help us in our struggle for action? Thanks in advance.

Yes, I can certainly let you know who I worked with––I just got my logic board replaced––interestingly enough, the authorized techs told me that the iMac 5k's video card/logic board are completely integrated, so when the logic board was replaced in mine, the video card was replaced as well.

I literally just got my iMac 5k back and powered on.

To those who are struggling to get Apple to give you a logic board replacement, I suggest contacting two people, first, the Apple Senior Advisor who, after much prodding, allowed me to replace the logic board, as well as a higher up in Apple Care who I would also contact.

The second person on this list, Tohnya Lenartowicz, is interested in Apple's engineers possibly getting their hands on a faulty machine, so you may luck out and she may take your malfunctioning iMac 5k off your hands and send you a brand new machine.

Senior Advisor: Vince Aker, Phone #877-416-4271, his direction extension: 1136787

AppleCare Tech who is possibly looking to acquire a fault iMac 5k for testing: Tohnya Lenartowicz, tlenartowicz@apple.com

REMEMBER that you need to be forceful with these people if you want to get the logic board replaced. You can reference this topic, and continually insist on the logic board replacement. Make sure they're up to date on everything you've done to try and solve the problem that has failed.

Well I got my iMac back from Apple today, but it's back to the beginning for me.

They specifically ignore community threads - as others have noted. They were unable to recreate the problem during their load testing. They declined to leave the machine logged in and powered on for the two weeks they had it while I was on holiday. I wasn't allowed a copy of the repair job case notes due to Data Protection legislation (it contains staff names?) but I could ask via a web chat and perhaps escalate to Apple Legal.

My allotted Genius today - supposed to be a senior technician, told me that this could be down to "environmental factors", "power surges" and "login items" despite it happening when all users were logged off... She suggested I plug the machine into a different power outlet and bring the power cable with me if there's a repeat incident.

I've been given no other routes to escalate the problem or short cuts if it recurs beyond starting a new case, quoting my previous case numbers and repair job IDs.

I've just reinstated my user data (only) from a Time Machine backup, as advised. Will keep an eye on the machine and install minimal other software to see if the problem recurs.

I've not yet had the invitation to feed back on my experience - guess how that's going to go?!

Mike

Got my iMac back last week with a new Logic Board but as of this evening (exactly a week later) this evening, it has shut down to black straight away, again. Turning it back on, straight away happens again. What a waste of time this problem is. Apple will be replacing the entire machine in this case. This is completely unacceptable.

I've just had another uncommanded restart, despite having loaded very few applications at all, so off we go to the start of the process again...