iMac 27" 5K Late 2015 screen artefacts on shutdown

I'm working since 6 days on 10.12.4 and had at least 30 shutdowns...

Every shutdown nice and smooth and ends black..... no artefacts

I suppose the artifacts that have been reported by other members have nothing in common with the original ones that were the reason for this post.

Why can't Apple inform transparently on what they have done with 10.12.4?

In fact of the matter is that they have a direct relationship. I have a new device - I installed the sierra yesterday. With full formatting. And the result - caught that moment. The screen is not all in artifacts, but still they are.

This is the exact same thing I had occurred after install the latest update except mine was in the lower right-hand corner. But I believe is, the VRam is corrupt or not properly flushed when shutting down.

It was in the upper left corner as in the photo, more often in the lower right. The problem is not fixed, I have a new device on my hands and it behaves so when I turn it off. I hope in September-October the new version of the operating system will completely eliminate the defect. Though it would be desirable, that was earlier.

It is my opinion that most of the remnant issue has been resolved. It has only happen to me once since the 10.12.4 mass Sierra update. My iMAC Retina 5K 27-inch late 2015 computer use to have a lot of issues but as I mentioned at the beginning the remnant issue has only happened to me once so far. The screen went dark by a series of black horizontal lines (about 1/2 inch wide) moving parallel down from the top until the entire screen was dark them it shut down normally. It appears to start back up with out issues after that and it only happen the one time so...?. Anyway, I hope this information helps.

CORRECTTED TYPOS FRO,M LAST RESPO\NCE:

It is my opinion that most of the remnant issueS haVE been resolved. It has only happen to me once since the 10.12.4 OS Sierra update. My iMAC Retina 5K 27-inch late 2015 computer use to have a lot of issues but as I mentioned at the beginning the remnant issue has only happened to me once so far. The screen went dark by a series of black horizontal lines (about 1/2 inch wide) moving parallel down from the top OF THE SCREEN until the entire screen was dark them it shut down normally. It appears to BE startING back up with out issues after that and it only happen the one time so...?. Anyway, I hope this information helps.

It is only my opinion that 97% has been corrected. Garage Band still does not work *( it won't update the apple loops) and the "artifact" issue while better does seem to occur once in a while. Yesterday, my screen had a wide black line move from the top of my screen to the bottom when I shut down my iMac. This computer is my second one as Apple replaced my original one. So while the artifact issue is much better I don't feel that it has been completely resolved but as I said this is only my opinion. I hope that helps you.

Me too, but I notice the shutdown glitches (blackout from top downward and a small scrambled rectangle) happen when I click on the "Shut Down" button with the screen cursor, which creates a last-second interaction with the screen buffer. My working theory is that these glitches can be avoided by using the Return key instead of the mouse/tablet to confirm the shutdown. We'll see.

This problem has recently occured on my 2015 CrapBook Pro; on shutdown, I see about 5 columns of dotted green lines in blocks of 3, and slightly slanted too. I have had one critical ssd corruption four months back in which I had to do a full reinstall of sierra. Then, just last week I had a minor corruption after messing with vmware fusion. OSX was running in a crippled state until I did the first aid on my ssd. Now, I don't exactly have any problems with performance, but seeing these green lines on shutdown is pretty **** pathetic for $1.8k machine. This is my first and likely -the last CrApple product I'm gonna buy. Oh how I wish I bought a PC laptop instead... somebody help me 😟

I had the same problem, it seems to be a unique problem with sierra, it was bugging me so badly I just downgraded back to El Capitan and it's been fine since.

I performed the downgrade about 2 months ago and it hasn't come up with any weird artifacts or lines on the screen. Before the downgrade it did it about about 2 or 3 times a week. To me it also seemed that if the computer was doing some intense tasks such as video editing or gaming I would be able to guarantee that it would do it. https://youtu.be/hrfsnIOyVr0

It has been quite some time since you updated to OSX 10.12.04. At that time you reported that the update appeared to resolve the startup artifact problem.

Now that a lot of time has passed since your update, perhaps you would be so kind as to share your "current experience and opinion"? Has the update permanently resolved the problem.?

In advance, thank you so much for you input!

The new OS update seems to have resolved 97% of the artifact issues and I only experience a 1/2 wide black line that moves horizontally to fill the screen upon shut down once in a while. This is a good update as far as I can tell but it does not fix any issues with Garage Band.

Not odd at all. I have been following these posts for some time and recently posted the previous update to the Sierra OS seemed to correct the problem 97% of the time. However, to up date this information I recently updated to Sierra version 10.12.5 and the artifacts seem to have reappeared in a new way. Last time I shut down there was a clump of multi-colored artifacts in the top center of my screen. My iMac shut down ok and started up with no issues (I am currently using it) but sadly it seems that this new update "Un-fixed" part of the issue. Just as an FYI I had been surfing the Web prior to this latest incident.

For the most part yes it corrected the artifact issue but did nothing for garage band which still will not update or work correctly. While looking the web using Safari there are times when I get about half inch wide black lines moving horizontally from the top of my screen down to the bottom when I shut down. This is very intermittent and noted the the websites but upon returning to it the problem does not replicate 100% of the time. I have noticed that the fan comes on and is loud prior to my shutting down and getting the artifacts. Apple was kind enough to replace my first iMac as it had terrible issues. In comparison this one is much better but is still less than 100%. I wish I had better news but it is what it is and Apple products (at least this one) does not instill confidence in future sales of their products at least to me. Please note that I have family members with older Apple computers and they have no issues at all and find my issues strange to say the least. Good luck and I hope this post helps clarify what is happening from my seat.

Corrected typos below. Sorry for the double post and will check more closely next time.

For the most part yes, it corrected the artifact issue but did nothing for garage band which still will not update or work correctly. While looking at the web (using Safari) there are times when I get about one half inch wide black lines moving horizontally from the top of my screen down to the bottom when I shut down. This is very intermittent and noted the the websites but upon returning to them, the problem does not replicate 100% of the time.

I have noticed that the fan comes on and is loud prior to my shutting down and getting the noted artifacts. Apple was kind enough to replace my first iMac as it had terrible issues. In comparison this one is much better but is still less than 100%. I wish I had better news but it is what it is and Apple products (at least this one) does not instill confidence in future sales of their products. (At least to me.) Please note that I have family members with older Apple computers and they have no issues at all. They find my issues strange to say the least. Good luck and I hope this post helps clarify what is happening at least from my seat.