iMac 27" 5K Late 2015 screen artefacts on shutdown

I'm seeing the problem (intermittently) with the standard video card for this computer, AMD Radeon R9 M395 with 2GB video memory. Is anyone seeing it with the upgrade, AMD Radeon R9 M395X with 4GB video memory?

I'm on my second (2nd) 27 inch retina iMac in a little over a month. Returned the first one and reordered a

replacement. Different video cards on each one, both special order builds with ssd drives. Both have the same issues on shut down with random weird screen artifacts.

I'm NOT a happy Mac user at this point! Back to the local Apple Store genus bar to see what they say this time.

Hi, Apple have been aware of this problem since the beta version of Sierra, then i went back to El Capitan after my iMac was showing the problem... So when the full version of Sierra was released i updated to it. Apple first tried to say wait for updates back in September.. so i did and the updates didn't resolve the problems.. so apple sent my 1st iMac 5k 27inch 1tb fusion drive And Radeon M390 2048mb off for repair they replaced the Screen HHD and logic board .. with no joy the problems still there back in October last year. Then respectfully they replaced my machine with one built in September of 2016. My iMac is unstable when running sierra

I have been speaking to a friend and we are able to take a class action against Apple..So they will have to start explaining when they are going to fix this problem or not so we are not left with iMacs what show signs of issues. as all what apple is telling people is to wait for updates which don't resolve the problem .. i have upgraded and downgraded every time when there is new update ..

I have spoken to apple today and they say the same thing, as i said (( this is like buying new microsoft laptop windows 10 and it only able to run windows 8.1 .. Apple do not know what is going on with these 5k iMacs so more people listen to them and getting throbbed off, less likely they will do anything ...

Just in case anyone might think this is being fixed in the latest beta, the priority is apparently: "dictation support for Shanghainese & cricket scores" which of course one can understand the overwhelming need for rather that fixing video glitches.

I have the issue ,too.

"horizontal or vertical lines appearing in Time Machine"

- and also a black rectangle in the Finder window. Very scary!

How could apple deliver such a product with this huge problem by its own software and hardware???

2/8/17 update. After two logic board replacements, it did it again on restarting the iMac this morning. Here, I thought it was fixed because it seemed fine for over two weeks since the second repair. Hoping Apple gets there act together soon. This is something I'd expect from a Windows machine, not a Mac.......

I agree. I have had this computer for over a year and 3 months, and all started when I updated to Sierra. I am hoping that someone out there is listening. Occasionally my wired mac keyboard also loses connection. I have unplug, and plug back in. Weird things a foot.

I don't understand why some people are going backwards and forwards to get hardware service on their Mac when this clearly must be a firmware or driver issue if it only happens to occur in macOS Sierra but not in OS X El Capitan. No amount of logic board or display assembly replacements are going to help until Apple provides a software update to address the problem.

I understand Apple is responsible for causing the problem and is certainly a poor demonstration of quality, but if it doesn't affect your use of the machine until you shut down your Mac, I'm struggling to understand why people find this issue so significant. Do these artifacts occur in the middle of using the machine?

Whilst I agree its a software issue and a waste of time sending the mac to be serviced, I'm glad people are doing this; the more that do, the sooner Apple might notice the rising cost of repairs and fix this problem.

The issue isn't significant in and of itself but what is significant is the length of time Apple has left this unresolved. Its a clear demonstration how macOS has been downgraded in favor of iOS.

I updated to the latest beta 2 and it hasn't glitched yet, but that doesn't mean anything aside from the hope that most other betas and releases have glitched on shutdown as soon as the update was installed. Wishful thinking I know, but I'll see. Sooner or later I'm hoping this gets a fix.

Has anyone tried increasing cursor size ?

did this a few days ago and not had any problems with screen at shutdown since might just be coincidence but worth trying

increase cursor size slightly in

System Preferences- Accessibility -Display

Cursor size change makes no difference. I use a slightly larger cursor - stops it from disappearing.

Recently I've had just a couple of shutdown artifacts, but the latest was more interesting - not stripes, but a page repeated across the screen - couldn't say exactly which, it went so fast, but it looked rather like a mail message.

The other case was not a full screen image, but a tiny one in the bottom right-hand corner of the screen.

Ok so. Just an update on this.

I logged this about a month ago. They came back and closed it due to it being a duplicate of another bug which I could see was open. Since they at least link the original bug number and status to your closed bug report.

I went in now and can see the original bug is closed. So I assume with the latest beta last night. Beta 3. This bug is now resolved? Can anyone confirm.

I don't have the iMac anymore.

I had this same issue recently. I have also seen issues when entering into Time Machine where there are strange artifact lines at the edges of the Time Machine Finder window that run the entire screen both vertically and horizontally.

Neither of these things seem to be causing any specific issue but my mac is not that old and it's worrisome.

Yep spoke to soon and it's back again! It looked like the iMac had gone to sleep but there was a thin multicoloured line at the top of the screen, the rest of the screen was black. Just shutdown and the entire screen was filled.