2020 iMac Screen Glitch on Shutdown

Hi FrankZ,

I have tried a lot with my new machine and also was on the verge of bringing it back... but that would mean a great deal/hassle for me because we need it for work i couldnt easily miss it.

So 2 weeks ago i wiped whole system clean 2 times and did the following.

1. wiped clean > installed Catalina (no issues) > installed adobe stuff (no issues) > installed Bigsur <issue appeared>
2. wiped clean > installed Catalina (no issues) > installed Bigsur (issue appeared)

So, for me that meant that it has to do with Bigsur... so now i am running system in Catalina and keep a close look at system if the issue will appear after using imac for longer period of time (because it only happens if you use the imac for some time around 15 minutes or so).

But so far... all good...

I can't get my head around the fact that Apple is nowhere to be seen in this issue... that's what's makin me seriously doubt if it still isn't a hardware issue... It's like the don't want to address this issue maybe for being afraid they (again) have to do a call-back action on thousands of machines with this similar issue?!!! Just not responding to this makes me wonder about that. Instead of being open and honest about what this issue might be and that they are working on a solution in the background....

But okay, that's probarbly just me....

i will respond to any of the comments placed here. Greetings.

Hello Guys, I have a brand new iMac 27 2020 i9, Big Sur. As you can see from the picture I got the same problem during the shut down or restart. It appears randomly, as many of you, if I use the computer more than 15 mins. Did someone understood if this is a OS problem or an hardware problem? Even if this problem is not affecting my work, is annoying coz I am worried that can be a hardware issue and in a future I don’t want to spend money for it. Thank you in advance for any reply

So here is a picture of the glitch happening during normal operations. If you are using more than one user you will experience the same issue.

I am happy that I got my iMac repaired (replacement of Logic Board) - since then I have not experienced the issue anymore.

I have the EXACT same issue. My 2020 iMac has the 3.8GHz 8-Core i7 with 5500XT 8GB graphics. I've tried resetting the NVRAM/SMC and reinstalling the OS, as well. This issue occurs with Catalina 10.15.7 and also with Big Sur 11.1.

P3-Mac, are you noticing the issue on your new (replacement) iMac?

Spinnetti, have you been able to resolve your issue?

Thanks for your help!

So, i had the same issue. Contacted Apple, couldn't give me any proper answer to the issue and i have been told that they didn't know about it internally??? I also sended them the link of this discussion. So new computer, fresh out of the box, installed adobe pack and some standard stuff and i noticed the half screen issue at shutdown. It flickers 1 time, then shows half opaque exactly in the middle before actually shutting down.

So, my thougth where this. A: or it is a hardware videocard issue. B: it's iOs issue so software... my bet would be B because it is only happening at shutdown. A defect videocard would probarbly also show other issues during usage of the imac.

They couldn't give me a proper answer and told me to return the iMac... fine, it would be the second one i would be returning so i was not in a hurry to do so because i must de-install everything on it (again) and will cost me a lot of time.

But.... and here it comes.... i decided to wait for next iOs update... and today there was one... and to my surprise... the issue seems to be gone!!!

So, i am very curious if this is also the case with some of you guys? so please update and see if it is indeed fixed as it seems to be here. Big Sur 11.2.1

Hope to hear from somebody soon.

I agree. It due to the bug of OS.

I have a exactly same computer and was working perfectly fine with Catalina. Lot of issues came to me after updated to Big Sur. the splitter screen during shutting down..... the ventilation fan is constantly on disregard the room temperature is only 65 degree....put hard drive to sleep but external HDD is randomly on and off during the computer sleeping..... it's annoying.

update to 12.1.1 solve the my split screen problem.

Studioviv,

Thanks for posting in this thread. You gave an excellent description of the issue we're having, and I was happy to see that your problem seems to be solved.

Unfortunately, the 11.2.1 update did not solve this issue for me. I can still reproduce the issue just like the original poster (P3-Mac) indicated in the very first post of this thread, "...when I turn the machine on and shut it down within say 5-10 mins NO split screen/hue glitch. But as soon as the Mac is working over say 15 mins, the glitch is evident on each subsequent shut down."

Are you sure that this issue is completely resolved for you? If you use your iMac for 20-30 minutes or longer without allowing it to sleep, does the issue reappear upon shutdown?

I'm hopeful that this is solved for you, but disappointed that the update wasn't of any help for me...

Mike

He Mike,

I see what you mean and indeed what your saying is what i experienced before... shutting down within a few minutes didn't show the problem. Using it for longer period of time, it did show the problem.

I haven't yet tried using the Mac for longer period of time yet (let's say 30 minutes plus) and yes i am a bit afraid it may show the issue once again then so i will test it out this coming week. But after the update i noticed it was not happening so i immediately was curious to see if anyone else had the same experience but as i am reading through the responses i am afraid it has not yet been resolved.

Will post if i have more feedback on the issue. P.s. i am finding it very strange that Apple haven't responded anywhere properly to this issue. It's so obvious that something is off here and let me assure you that a lot more people then just us will have this same issue. A lot of users will probarbly ignore it because it's not something which interfears with our work.... the mac is working and who is actually watching the shutdown process??

Really odd. Mac should be the topnotch computer brand so why don't they act on this. You cannot tell me they don't know about this problem, no way, they do. So perhaps we should bring the issue into a bigger audience?

Hi everyone - thought I'd chip in on this. To me this is an OS issue and not hardware related. It would be unreasonable firstly to think we all have faulty graphics cards although of course, that's not impossible.

This glitch happens for me on my new iMac on shutdown as described by everyone in this thread. Out of curiosity, I reinstalled Catalina and I cannot get this glitch to replicate with that OS so that (I'm no techie) suggests to me it's software related.

it would be nice if Apple could acknowledge and release a fix for this as it's more annoying than anything else. I don't like buggy software.

Anyway, just wanted to report what I had found testing this out.

I have version 11.2.2, the latest update to date. I have the same problem here when restarting and shutting down. Called Apple today, shared my screen with them for them to look at, but still couldn't figure it out. So they scheduled me an appointment at the Genius Bar for tomorrow. But I'm not sure if I should bother unplugging all the cables, packing it in the box, unpacking it at Apple, packing it back in the box again, unpacking it at home, and finally plugging all cables back in only to be told that it is a software issue and that they would hopefully fix it with the new update.

Pretty sure it’s not hardware related as previously mentioned. I can’t get this to replicate with the previous OS and apart from this glitch on shut-down with OS Big Sur, I have no other screen issues, again consistent with everyone else reporting this shut down Big Sur issue.

Agree on it most probably being a software issue and hardly a graphics card fault that only appears on shutdown. My 2020 iMac does split hue on shutdown too, my late 2015 iMac does not. Both are on 11.2.3. As long as I do not see this happening once during normal operation I will not bring my iMac anywhere. I would immediately notice a split hue while I'm working and since I got it in December 2020 and it has been running 8am to 6pm every weekday (at least) and some hours on the weekend I am pretty confident it is just a software issue during the shutdown process. FYI regarding hardware the iMac screen actually consists of two separate screens placed next to each other. So for sure an issue driving the two screens on shutdown. Fingers crossed it'll be fixed in one of the next updates.

I have the same problem. I have a brand new Mac with Intel Core i7, AMD Radeon Pro 5500 XT 8 GB and with the latest OS (macOS Big Sur version 11.2.3). The problem accurs during shutdown but only if my computer first goes to the sleep mode.

I have already replaced the screen with a new one but it didn't solved the problem. Apple says that it's probabley a software issue.

I have also a flickering screen issue when I log on to the computer and a change of color when entering my desktop. Hopefully Apple will solve these issues with the new update.

Ava_Jt, thanks for adding your info to this thread.

You mention that you have a "change of color when entering my desktop." This might be normal behavior caused by the True Tone feature, which adapts the display to keep colors consistent under various lighting conditions. To check, go to System Prefs --> Displays and deselect True Tone. Try restarting with True Tone off; then with it on again. See if that makes a difference.

Mike