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

The corner glitch was very annoying specially after I spent $4000 for that iMac. That’s why I returned it. I also called Apple Care to see if they fix this issue and guess what they said?

They didn’t even know this problem exists...! I told the tech dude: are you guys serious? It’s all over the internet. He said sorry he can’t help me. I’m a huge fan of Apple. I have ALL their products but this time I am very disappointed. I hope they fix it soon and train their tech people.

A complete crash when playing Civilization VI through Steam for 10-15 minutes is exactly what I am experiencing. It just freezes and then starts visually falling apart. Can't force quit because mouse, image, and everything is non-functional. Have just done my second hard reboot, just to get the machine working again at all.

Such a disappointment. I was really hoping that the latest update (that fixed the random lines glitch) would also fix the complete crash bug we both experienced. I returned my iMac back then and have been in a limbo since the latest update whether to buy again or just go for PC setup. I guess your post has just answered that question for me. Thank you for your update on the matter.

You’re welcome. Honestly I would wait for them to fix this mess (Hopefully soon). I’ve been a MacBook Pro and iMac user for many years and this is the first time Apple messed up like this.

I’m really mad cuz I spent $4000 on that iMac and because of their fault I had to return it. I need an iMac for work but I guess I gotta wait till Apple fixes it. By the way I hate PC (No offense to anyone)

I've had my machine 10 days now, and, after upgrading the machine 10.15.7 right after first boot, this has been my experience, too: no line glitches, no window corner issues (using dark mode, with the Half Dome Night Sky as the desktop background image). Don't know if that would apply for normal mode and a brighter or darker background image.

I've had exactly one game-related glitch in ten days. I don't play Civ <anything>, but playing the WoW Shadowlands beta last week, the game hung up when I was trying to switch characters (that is, in the character section screen, not something I would have thought of as graphics-intensive). Locked hard, non-responsive to command-option-escape or anything else I tried, and did a variety of odd graphics things. Could have been the card, could have been the driver, could have been the net s/w. Nothing like that since, and certainly haven't tried tuning the long list of graphics settings; will wait for the "retail" (release) version for that.

Do let us know how it goes when you start to max out the graphics settings of your game. I checked it out on YouTube and it looks like a game that should demand more GFX than Civilization VI. If you can manage to max out your game and still run stable, we should be good overall.

I'm probably not the best stress tester: I have most graphics settings squarely in the middle of the various ranges, and the game looks terrific. I do, however, use the "real" native resolution, 5120 x 2880. I realize the effective resolution is only half that, but with the amazing dynamic range of Retina displays, that resolution gives me much higher contrast, which helps my geezer eyes a lot. Even at that resolution, I'm able to maintain 60 fps in almost all environments other than raids, which I don't do because of the visual overload, among other reasons. The 60 fps figure is 33% - 50% better than I could eke out of my previous machine, a 2017 CTO 27-inch Retina 5K iMac with the top graphics option. I'm very happy with the system so far, and am neither surprised by nor upset by the fan sound when doing graphics-intensive things.

I had one experience like that a couple of days after receiving the machine (~ October 19), but not since. I've been keeping up to date with OS patches; don't know if it had anything to do with that. I use TG Pro, but currently only with the default settings, which are set to spin the fans all the way up (~ 2700 rpm) when the average CPU speed hits 50 C. May tune that as time goes on.

I'm not suggesting anyone switch to dark mode just because of this, but I will note that I've been using the i9/5700XT model I bought a month ago in dark mode with no indication of the corner issue. Would be interested if you or anyone else experiencing the issue tested dark mode to see if it persists.

Edit: Just checked "normal" mode.... and no sharp corners there, either. Running 10.15.7, up to date with all patches.

So the Mac is still being shipped without the latest version of Catalina? No one reads any of the 17 pages of this thread?

The M1 solved my dilemma: Going to give up on the idea of iMac and go with Mac Mini. Never did like it when Apple dropped the matching monitor for iMac.

(Finished cleaning up my Outlook mail yesterday. Gave up on counting the number of emails I had received AFTER the resolution.)

https://www.apple.com/feedback/imac.html

[Edited by Moderator]

I guess the drive to Brea, which is open, is prohibitive? And smokey.

https://www.apple.com/retail/breamall/

I have had worse issues with 2020 27" with 5300

Has been returned and replaced.