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Apple in August refreshed the 2020 iMac lineup with a new 27-inch model that's equipped with 10th-generation Intel processors, more RAM, more SSD settings, and faster AMD GPUs.

imac-27-inch.jpg

Unfortunately, some new Mac owners have been running into problems with their machines and have been reporting ongoing glitching with the graphics. There's a 57-page thread on the MacRumors forums filled with complaints dating back to August, suggesting this is a problem that's been impacting iMac owners since the new Macs came out.


Based on a poll, a good number of iMac owners who have the higher-end 5700XT GPU are seeing a white horizontal line flicker across the display on occasion, but the problem does not seem to impact all users. MacRumors reader torifile describes the issue:
I got my 2020 iMac Thursday night. It's as fast as expected and gorgeous. Last night I thought I saw, out of the corner of my eye, a horizontal white line flash mid-way up the screen. It was really fleeting and I thought I was just seeing things. This morning, I saw the same thing. The computer isn't running hot or anything. iStat Menus has all the cores untaxed. I recall having this same problem with my MBP 13" (2019) with an earlier version of macOS (I can't remember if it was a late Mojave build or an early Catalina) and it was cleared up with a software update.
The white line described by those affected appears to flash across the screen at random intervals throughout the day, and there are some other seemingly related graphical issues that iMac owners have run into. Some users have reported being able to remedy the problem by choosing a scaled resolution other than the default, but that's not an ideal longterm solution.

It's not clear if the issue that iMac owners are experiencing is hardware or software based, but Apple has not yet implemented a fix for the problem.

Article Link: Graphical Glitches Plaguing Some 2020 iMac Owners With Radeon Pro 5700 XT GPU
 

dantracht

macrumors 6502a
Sep 19, 2013
870
2,497
I've owned the new 2020 iMac with 5700 XT and haven't noticed any graphical glitches yet but maybe they're happening and I'm not noticing. That said, I've had LOTS of other problems with the machine this just isn't one of them.
What problems? Sorry you have to go through that!
 
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Dwalls90

Contributor
Feb 5, 2009
5,225
3,504
Is this the same 5700 XT that's desktop class and fairly powerful as a gaming GPU? Or is this a watered down mobile version? Curious if the GPU is overheating and if this is a thermal issue.
 

dguisinger

macrumors 65816
Jul 25, 2002
1,005
1,755
I wish MR would write a big piece on the 16" GPU issues.
Unless there was one but I don't recall.
Ultimately AMD drivers / hardware sucks lately.

16" GPU issues?
I sometimes get applications that corrupt their screens, I always assumed it was a Catalina issue. It forces a restart for me to clear it.

I also get a lot of Core Audio issues like videos that no longer play audio that forces a restart. I've had it up to here with these issues, whether its hardware or Catalina I'm quite pissed that I have several major recurring issues that impact me daily that never get resolved.
 

LittleByrdEee

macrumors newbie
Aug 17, 2019
2
2
So far, since August 24th the 5700 XT 16GB variant I chose has been working perfectly. I will keep a look out but currently switched to BigSur this week when the new beta was released with 2020 iMac support.

Also have used BootCamp + Flight Sim and was able to handle the game.
 

jlocker

macrumors 65816
Jun 20, 2011
1,014
1,184
Lake Michigan
Sounds like some kind of graphics driver issue bug that needs to be found and fixed. There are always graphic driver updates needed on new chips to find some kind of firmware or driver code problem. Has been happening since computer first came out. They will find it and fix it. The best thing you can do is report it to Apple with Feedback and explain and document, photograph to help them find the bug.
 

ninecows

macrumors regular
Apr 9, 2012
166
144
I had mine for two week before I saw it. But then I got it several times. I cannot rule out that it’s been there all the time

There’s also a glitch with the upper left corner of some apps. It’s supposed to be round but there’s some flickering squared corner. This is easier to reproduce.

Since it’s hard to spot and reproduce I think all with 5700xt have it. Many users have received 1-2 replacements that also have it. That increases the odds for all units being affected quite a lot.
 

dragoon2745

macrumors regular
Jul 12, 2017
104
378
Minneapolis, MN
What problems? Sorry you have to go through that!
It was mostly in the beginning. For example the first time I plugged it in and hit the power button it wouldn't turn on noting it still had the default RAM. I tried different surge protectors, plugging it directly into wall outlets I knew functioned properly, trying to use the power cord from my old iMac, nothing. I figured I got shipped a lemon. After googling this for an hour, I just randomly tried it again with my fingers cross and it worked and haven't had a problem since. No idea what was going on... Other issues involve crashing where I have to press and hold the power button, random restarts but no kernel panic screen, and apps crashing that never had a problem on my 2012 iMac. This didn't happen enough to make me want to do a 14 day exchange but I also have AppleCare if I have a hardware issue in the next three years.
 
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jpsalazar

macrumors member
Sep 16, 2020
46
42
Sounds like an emerging issue. Definitely something to keep an eye on. iMacs with high-end graphics chips are typically not prone to these kinds of issues.
 
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photomek

macrumors newbie
Sep 9, 2012
21
4
Germany, Paderborn
That's interesting. It seems to be exact the problem I (and some others) experience with my Mac Pro 2013 (Dual D500 graphic cards) since Mojave. It became worse and better through the updates, but I never got really rid of it. Today with latest Catalina Updates I still see it randomly, but mainly when scrolling up or down. See this thread: https://forums.macrumors.com/threads/mac-pro-late-2013-gpu-driver-issues.1860297/

When installing Mac OS High Sierra there is no graphic glitch at all. So I am still convinced it's a driver issue here. May be this is getting more attention now and there will be a fix for all of us. Let's hope at least. ;)
 

InTeCredo

macrumors member
Aug 14, 2017
31
37
When will Apple learn from its frequent fudged-up issues with graphics processor units? First, it was the GPU welded to the bottom of the motherboard in iBooks (Dual USB) that got detached due to the frequent heat expansion and shrinkage cycles. Then, it was the Nvida GPU for MBP debacle that ended the business relationship with Apple for good.

Not to mention some GPUs killing any possibilities of upgrading to Mojave and higher. My 27" iMac (Mid-2010) couldn't be upgraded to Mojave due to the Radeon 5xxx GPU not compatible with Metal. That sucked big time because Apple iBook app (High Sierra) can't display the highlights and notes I made on my iOS devices with iOS 11 and upward: they requires Apple Book app which can't be installed on High Sierra. Recently, I found a workaround that worked decently when installing Mojave on my nine-year-old vintage iMac by copying a specific AMD driver from High Sierra to Mojave.
 
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insomniac86

macrumors 6502a
Oct 13, 2015
528
767
Perth, Western Australia
I wish MR would write a big piece on the 16" GPU issues.
Unless there was one but I don't recall.
Ultimately AMD drivers / hardware sucks lately.

I’d say AMD hardware lately has been great. AMD has been closing the gap with nVidia’s performance lead. ATI/AMD drivers on the other hand, for the past 15 years they have been known in the PC world to be crap.

Now we have to see how AMD’s RDNA 2.0 competes with nVidia’s Ampere.
 

Grohowiak

macrumors 6502a
Nov 14, 2012
618
662
I’d say AMD hardware lately has been great. AMD has been closing the gap with nVidia’s performance lead. ATI/AMD drivers on the other hand, for the past 15 years they have been known in the PC world to be crap.

Hardware is nothing without software and in this case there's no one without the other.
Paper specs mean nothing if I can't just make it work.
I can plug any nVidia card into my eGPU, run bootcamp and have it recognized right away while to run a amd I literally have to run around the world without a guarantee that it won't crash in the end.
 
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insomniac86

macrumors 6502a
Oct 13, 2015
528
767
Perth, Western Australia
Hardware is nothing without software and in this case there's no one without the other.
Paper specs mean nothing if I can't just make it work.
I can plug any nVidia card into my eGPU, run bootcamp and have it recognized right away while to run a amd I literally have to run around the world without a guarantee that it won't crash in the end.

Sure, but crap drivers doesn’t mean the hardware performance hasn’t increased.
But I agree that with rubbish drivers you still end up with a crap stability.

But it’s not the fault of the hardware. You do realise that PS4, PS5, XboxOne and the new Xbox all use AMD graphics and they are stable as.

Let’s see how Apples GPU’s compete soon!
 
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