iMac 27 inch 2020 - Screen Glitch (Random Lines Appear on Screen)

I've just received my new iMac and noticed that from time to time a line glitch appears on my screen.

It's completely random, I thought it was related to intensive work/heat but sometimes even when the computer is idle I see the line on the screen.


It was really hard to capture it because it's so random, but I manage to record the moment a glitch happens. Unfortunately there's a lot of white background on it which makes it hard to see, but it goes across the entire screen https://www.youtube.com/watch?v=xw8Z4mVgYgE


The iMac is running fine, I ran all sorts of benchmarks for CPU/GPU and it's all OK, but from time to time I see this annoying line on my screen.


iMac Line (2012 and Later)

Posted on Aug 26, 2020 7:21 AM

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Posted on Nov 8, 2020 2:27 PM

Try the following: download and apply the macOS Catalina 10.15.7 Combo Update   


It fixes this issue:


• Addresses a graphic issue that may occur on iMac (Retina 5K, 27-inch, 2020) with Radeon Pro 5700 XT


249 replies

Sep 2, 2020 12:57 AM in response to aagodoy2

I've decided to return my unit. It's a to expensive buy to count on it being a software issue. Return of sale rules are of course different from country to country. 14 days after an online purchase in my country and I can no longer return the unit for anything else than a repair or replacement which won't do me any good if it's a general hardware failure. Better wait this one out.

Sep 5, 2020 8:37 AM in response to aaronshort

I was considering the same. Was gonna return my i9 5700XT and get an i7 5700.


But despite what most of the reviewers are saying, I realised I will be actually able to utilise the plus 2 cores since I'm compiling in Xcode often, need perf bursts for multitasks and also running VMs regularly.


Not decided about 5700XT vs 5700 yet though. Have just bought a headless "dummy" hdmi plug which I'm gonna connect now to simulate a second screen being connected and if the glitching issues won't manifest themselves, I'll keep mine as is.


Got by the end of next week to decided if I'm keeping it

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iMac 27 inch 2020 - Screen Glitch (Random Lines Appear on Screen)

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