iMac 27" 5K Late 2015 screen artefacts on shutdown

I wish I had read all these posts before buying / returning 3 iMacs during the last month. I've tried 2 different models (M390 and M395 GPUs) and BOTH of them have this shut down issue.

It's weird that Apple Store employees were not aware of this issue...

Why this has not been addressed seem to be a priority issue with bugs...seems to me that one of these betas should have done it. Worried this is more than software now that most of my units are out of warranty.

I'd just like to add that I have been following this thread and have the exact same problem all of you have. My lines upon shut down were very random for the last month or two, but now seem to occur each time I shut down.

I have the exact same issue, it some times wont do it for a few weeks then suddenly it will do it every time I shut down or shutdown and reboot. It doesn't matter how many times I speak to Apple, they look into it and I don't hear anything back from them even if I send them an email to the person who I have spoken to they never return my emails, Apple customer care is crap - I doubt I will ever get another one of their computers again! It took them nearly a year to get my iMac booked in to get repaired, as soon as I purchased it it used to just reboot without warning and the fans would spin up, I kept telling them it was a hardware issue, in the end I lost my temper with them and they finally got it in for repair - turned out the logic board was faulty they replaced it and it has not done it since. Then this issue with the coloured lines on the screen, I wanted them to replace it but they wouldn't they said they will try and fix the problem but they still have done nothing to rectify it, I can't even find anywhere where I can make a formal complaint about the way I have been treated, so this is the next best thing I can do.

My last iMac was a mid 2011 21.5" model and I had no problems with that at all so this is why I decided to buy another, I wish I never bothered. - Apple don't seem to care that their customers are unhappy they have our money thats all that they care about.

anyway rant over - for now!

I thought I'd give Apple support another call. Each time I call in I get a different response.

A few weeks ago, when I first called support for THIS iMac (returned the previous one for same issue), they gave me the vague answer that there would probably a fix in an upcoming version of Sierra. This past week, a different support rep told me that this was something they'd never heard of before, and forwarded my information to the Apple Engineers. Note** She suggested that going through support would be the ONLY way they would catch wind of the problem, so I hope everyone here has tried to go that far.

She then told me to book an appointment with the Geniuses--but after reading this forum, I see no point in playing with random hardware replacements. I already replaced this iMac once, and the problem only appears the moment I upgrade to Sierra.

I made the decision to extend Applecare in case this does prove to be hardware (probably their plan all along). I really hope they figure something out in the next two years. That should be ample time, no? Considering the high-end Windows rig I could have for what I paid on this iMac, I'm really starting to question my decision on choosing Apple.

P.S. I've found a novel solution in the meantime: Don't turn off the iMac.

According to Apple Support, it uses more power to turn it on and shutdown each day. The few times I've left it running for a week, I also haven't had the glitch on shutdown.

I agree with you, I am doubting that I made the right choice with Apple this time, at the start of my problems with my Mac I have taken in back to the store twice they found no issue with it as I said above it finally went to a company called Amsys which found a problem with the logic board they replaced that, and the unexpected reboots have now stoped and now I have this annoying issue with the artefacts lines appearing on the screen. But if I compare my old Mac with this one - my old one performs much better in terms of speed and smooth graphics with scrolling etc. Apple have really cocked up this version of their OS that is, if it is that causing the problem. otherwise they have cocked up the 5K iMacs - sort it out Apple!!!

My iMac will go through stages it will be fine for a couple of weeks then suddenly it will do it on every shutdown - I think it also happens more frequent if I am giving it heavy work like video editing or gaming.

This is a common subject with these computers. After drinking around with mine for about a year or so Apple finally decided to replace my iMac. The new one seemed to work fine for the first few weeks then the multi-colored lines came back on shut down. Apple has done a poor job in addressing this issue and can't seem to find what the problem is. You might take note of place you go to online. I have started to track mine and there are a few that I visit seem to exacerbate this issue. The problem is with the lack luster performance of Apple Corporate taking this matter seriously. Keeping your computer on 24 /7 isn't fixing the issue it is only avoiding it. Come on Apple fix your stuff before a bunch of us go back to a PC.

I am sooooo glad I just found this thread. I have a brand new iMac, 27" 5K Retina Late 2015, just bought it a month ago. I get the colored bars on shutdown, only occasionally. The Apple technician had me do the SMC reset, no change. He said he was going to engineering, but I haven't heard back from him. But it doesn't seem to be a problem as it's not affecting anything. So for now, I will just live with it, with the comfort of knowing that it's not happening in just my computer.

Quick update: two weeks ago I did a clean system install then changed the resolution to 2880 X 1620 (the one just to the right of "Default"). I shut my iMac 27" 5K Late 2015 down every evening (and sometimes reboot repeatedly throughout the day) —I've seen no artifacts on shutdown whatsoever after doing those two things. YMMV.

I think this issue is significant, for what you spend to buy this IMAC don't you think it should function the way it's suppose to. My imac late 2015 27" 5k does the same thing right out of the box after updating the OS. This is my first Imac, 5 days old and don't shut down the right way, might be a sign of things to come😠. I'm returning it back to store and I'll go back to a PC 🙂.

I am on my second iMac as Apple replace my first one. The "artifact" issues while better still happens. I have been following all the messages (and there are a lot) it would appear that a bunch of people with the same iMac have the same issues ad while "Apple engineering" is supposedly looking into the matter the build was 2015 this is 2017 and no fix yet. So... take it from there. Apple has my money once and has no refund policy, tech support try to help early on but then they to get frustrated and stop talking to you or say, "We are working the issue and will get back to you." They don't seem to remember the get back to you part. Good luck..we all could use a bit of that.

All,

Just to add that I purchased a brand new iMac and have the exact same issue. In a way I'm pleased that it isn't a hardware fault and hopefully something that can be fixed with an update.. Heres hoping!

I will try and change my resolution setting as per some of the comments in this thread and report back..

D

Just updated to 10.12.4. I don't want to jinx it, but haven't had the artefacts on the last 3-4 shutdowns. Will be more confident after a few more restarts.

I opened the same set of applications that were almost guaranteed to set it off before, and it's been good. Fingers crossed it doesn't occur again. Anyone else have issues yet with the new release?

I did notice shutdown time have been significantly increased at some times since the update, but nothing over a minute or so in the worst case. I'll take that any day over apocalyptic multicoloured lines of doom.