iMac 27" 5K Late 2015 screen artefacts on shutdown

Couldn't agree with you more! From what I have read there are a number of people who have been given numerous replacements only to find the problem still exists on their replacements, the only real fix is to downgrade to El Capitan.

Saying that, so far since upgrading to the latest OS release last week I have not been plagued by the dreaded artifacts, but time will tell.

I Get the artefacts on shutdown with by thunderbolt ext hard drive plugged in but when I disconnect it a clean shutdown

I'm sometimes experiencing the same graphic anomalIes on shutdowns AND occasionally on Startup I get the message that my external drive was not properly ejected.

My iMac (27"/5K/4.0GHz/late 2015/AMD395X) is 1 month old.

I have downgraded the OS to El Capitan (10.11.6) and the problem gone!

But now I'm having another problem 😕, please see this:

http://sendvid.com/48ez0t9z

Please advise

I know. Don't worry, that's the bug that comes with that version. There's always something. Important thing, it isn't a hardware error. When everything is fixed, there'll be a totally new OS version. I'm experiencing trouble with syncing the NOTES app. It only syncs in one direction. I try not to bother. Happy Xmas.

But I'm getting this bug at every time I start my machine, is that normal?

Yes

This is weird: The problem did not occur for one week or so, after de-installing "Dr. Cleaner." This app seems to be responsible for some ordinary crashes, too... I cannot say whether it is solved now, but I am curious. ;-)

Thank you.

Hi All,

Just thought I would share my experiences here, having owned Apple Mac's for over 25 years, running a publishing company, I now work from home and upgraded from a 2011 27" iMac to the following spec:

iMac Retina 5K, Late 2015. 3.2Ghz i5, 2048 R9 AMD Graphics, 32GB ram upgraded from new (not apple ram, but direct from micron).

I was really disappointed from the start with the performance of my new iMac, it didn't really seem much faster than the old 2011.

I was in contact with support from the start, I won't bore you but 8 month's of reinstalling the system, sending off logs and having remote tech's looking at things did nothing, the machine ran slow, had beach balling, froze and had strange screen lines on shutdown and sometimes during video playback.

Sometimes the problems would be constant, then it would be fine for a day or two, the iMac was only 8 months old but Apple would not replace, even after screen shots, videos, and Etrecheck logs, I agreed to drop my machine off at one of the Apple repair centres, they could not find a problem, it was left with them for nearly 2 weeks, after a huge debate it was agreed to replace the logic board (this was based on information I had seen in other posts here) I had the machine home and still the same problems.

Apple would still not replace the iMac even though it was still only 11 months old, it got to the point of me having to take further action, someone mentioned changing the ram due to either crucial or OWC, the ram I got with the machine from new was running at 1600 the new 32gb from crucial runs at 1867mhz, everything seemed better for a week, today I have had two crashes and the screen lines are back on shutdown.

So to confirm, I had the logic board replaced by Apple, brand new crucial ram 4 x 8gb 1867mhz, I also did a complete safe mode install of Sierra onto a low level formatted HD.

I only have the bare essentials and no cleaning, virus checking apps etc..

I run Microsoft office, and Adobe PS, ID, IS.

My Etrecheck shows the iMac running fast 1.48 with no errors, I posted this to hopefully might make you think twice before spending hours re-installing etc.

I don't know my next move, hopefully something will be posted in these forums soon, Apple have confirmed they will have it in again for repair, but I can't lose the machine for another 2 weeks - I do have 3 years extended care.

Here's watching with fingers crossed.

Is this problem solved with the latest beta version?

Sorry I don't do betas. But somewhere in this tread, page 2 or so, someone mentiones beta .3 still has the bug.

I really don't know Apple know this bug report and they are fixing it or not?

Same here, all Mac's in my office with EL'Cap have not shut down screen issues. All Mac's with Sierra, corrupt shut down screens. It is random, but most concerning.

Apple, please fix or comment.

The bug has returned! I hadn't seen it since the most recent update but I just shut down and it came back.