Become a MacRumors Supporter for $25/year with no ads, private forums, and more!

iMac 2020, 5700XT - graphical glitch?

Please select GPU type and if you see the flickering glitch on the display:


  • Total voters
    172

torifile

macrumors regular
Original poster
Aug 10, 2020
141
127
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.

Anyone else noticing flashes of graphical issues?

iMac 20,2
3.6 ghz, 10 core
5700XT
32 gig OWC RAM (OEM RAM has been removed)
2TB SSD
 

PieTunes

Contributor
May 6, 2016
763
1,104
San Diego, CA
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.

Anyone else noticing flashes of graphical issues?

iMac 20,2
3.6 ghz, 10 core
5700XT
32 gig OWC RAM (OEM RAM has been removed)
2TB SSD
You're seeing that too?! So I'm not going crazy! I was just about to post something when I saw yours!

I have the 3.8GHz i7 with 5700XT, 32GB Crucial RAM and 1TB SSD. I started noticing these white horizontal flashes at completely random intervals when I was setting up my apps and whatnot. At first I thought they could be attributed to my fiddling with the Music app, syncing/downloading my music from iCloud, because the Music app would randomly have all the album cover artwork flash while stuff downloads. The flashes were always out of the corner of my eye but noticeable. They don't happen often, and they're extremely quick, but it's enough to make you first question your sanity.

I then started noticing them in other apps and doing other tasks, like scrolling/reading in Safari or when I'm composing an email, etc. They don't seem to occur inside the active app itself, but seemingly off to the side like somewhere in the background, sometimes towards the top of the screen, sometimes middle, etc. Very noticeable if you have a dark background. I've had the machine 2 days now, last night I turned off True Tone so when I use the machine later today I'm interested to see if that changes anything.

Besides this little glitch, everything is perfect. When you tax the system and video card running benchmarks and whatnot and your fan is going, I haven't noticed them happen at all. This makes me think it's (hopefully) a driver/software glitch within macOS itself, with the system being so new. I really don't want to have to box up and exchange such an otherwise beautiful machine.
 
  • Like
Reactions: mechapreneur
Comment

kkh

macrumors regular
Aug 22, 2020
206
141
Posted this already in another thread. Thanks PieTunes for the heads-up on this thread!

3.6 GHz 10-Core Intel Core i9
32 GB 2667 MHz DDR4
AMD Radeon Pro 5700 XT 16 GB

And... some issues. See attached. The rounded corners of Finder windows, specifically, appear either a) not rounded, b) appear to have extra pixels, or c) flicker as you resize the windows. And I have seen an occasional white line glitch across the screen. Rounded corners in apps like Safari are fine. Seems to be limited to Finder windows only and apps like TextEdit. Ran Unigine Heaven for quite some time with no issues. Assuming it's the 5700 and, weirdly, something specific with the Finder windows only.
 

Attachments

  • Screen Shot 2020-08-22 at 8.13.03 AM.png
    Screen Shot 2020-08-22 at 8.13.03 AM.png
    1 MB · Views: 517
Comment

PieTunes

Contributor
May 6, 2016
763
1,104
San Diego, CA
@kkh I haven't noticed any issues with the rounded corners in finder or the extraneous pixels in those places. I've been opening and closing Finder windows, squinting in the corners as I resize windows to see if anything looks odd but nothing so far. Resizing finder windows don't result in any stuttering or flickering for me.

Just curious, do you have True Tone enabled?

Also, just for idle curiosity, here's the Graphics section of my System Info. Do your details match, like ROM revision?

All in all I'm leaning towards this being just a software glitch baked into macOS and is hopefully fixed in a coming update. I wonder if anyone with a 2020 iMac with the 5700XT installed the Big Sur beta and whether or not they're experiencing the same thing.

Screen Shot 2020-08-22 at 9.02.32 AM.png
 
Comment

ADGrant

macrumors 6502
Mar 26, 2018
471
260
Posted this already in another thread. Thanks PieTunes for the heads-up on this thread!

3.6 GHz 10-Core Intel Core i9
32 GB 2667 MHz DDR4
AMD Radeon Pro 5700 XT 16 GB

And... some issues. See attached. The rounded corners of Finder windows, specifically, appear either a) not rounded, b) appear to have extra pixels, or c) flicker as you resize the windows. And I have seen an occasional white line glitch across the screen. Rounded corners in apps like Safari are fine. Seems to be limited to Finder windows only and apps like TextEdit. Ran Unigine Heaven for quite some time with no issues. Assuming it's the 5700 and, weirdly, something specific with the Finder windows only.

Unigine Heaven is an OpenGL benchmark. Have you tried any Metal benchmarks to see if they exhibit any strange behavior?
 
Comment

torifile

macrumors regular
Original poster
Aug 10, 2020
141
127
I’ve tried both Unigine (OpenGL) and Geekbench (Metal) benchmarks. In neither of them did I see any glitching.

I have true tone enabled and, coincidentally, that’s what caused the graphical glitching in my (and others’) MBPs.

I didn’t specify this in my original post, but as @PieTunes said, it’s a white line in an inactive window. I’m installing boot camp now and we’ll see if it occurs under Windows too.

I haven’t noticed any drawing issues in finder windows.
 
  • Like
Reactions: PieTunes
Comment

kkh

macrumors regular
Aug 22, 2020
206
141
@kkh I haven't noticed any issues with the rounded corners in finder or the extraneous pixels in those places. I've been opening and closing Finder windows, squinting in the corners as I resize windows to see if anything looks odd but nothing so far. Resizing finder windows don't result in any stuttering or flickering for me.

Just curious, do you have True Tone enabled?

Also, just for idle curiosity, here's the Graphics section of my System Info. Do your details match, like ROM revision?

All in all I'm leaning towards this being just a software glitch baked into macOS and is hopefully fixed in a coming update. I wonder if anyone with a 2020 iMac with the 5700XT installed the Big Sur beta and whether or not they're experiencing the same thing.

View attachment 946628

Our card specs look identical:

Screen Shot 2020-08-22 at 10.04.19 AM.png


TrueTone (or any other display settings) seem to make no difference. I toyed with some Accessibility settings (stuff I would normally not touch) with varying results.

I set my desktop to black and this is Mail:

Screen Shot 2020-08-22 at 9.55.32 AM.png


So, it looks like it's missing the alpha information completely? Some kind of a screen buffer issue? As soon as I move the window, it flickers on and off, sometimes accompanied with screen-wide white lines (which come and go super-fast and are barely noticeable).

Hoping this is a software fix after just spending two days on re-installing everything I need. :/
 
  • Like
Reactions: RyanXM and PieTunes
Comment

kkh

macrumors regular
Aug 22, 2020
206
141
Unigine Heaven is an OpenGL benchmark. Have you tried any Metal benchmarks to see if they exhibit any strange behavior?
No isses in Heaven or Geekbench
[automerge]1598116297[/automerge]
No isses in Heaven or Geekbench
Just as I posted that, a white line flashed on/off, to the right of Safari window.
 
Comment

kkh

macrumors regular
Aug 22, 2020
206
141
I’ve tried both Unigine (OpenGL) and Geekbench (Metal) benchmarks. In neither of them did I see any glitching.

I have true tone enabled and, coincidentally, that’s what caused the graphical glitching in my (and others’) MBPs.

I didn’t specify this in my original post, but as @PieTunes said, it’s a white line in an inactive window. I’m installing boot camp now and we’ll see if it occurs under Windows too.

I haven’t noticed any drawing issues in finder windows.
The white lines seem to be limited to the desktop, not any active window. Whether a solid color or an image.
 
  • Like
Reactions: PieTunes
Comment

PieTunes

Contributor
May 6, 2016
763
1,104
San Diego, CA
Our card specs look identical:


TrueTone (or any other display settings) seem to make no difference. I toyed with some Accessibility settings (stuff I would normally not touch) with varying results.

I set my desktop to black and this is Mail:


So, it looks like it's missing the alpha information completely? Some kind of a screen buffer issue? As soon as I move the window, it flickers on and off, sometimes accompanied with screen-wide white lines (which come and go super-fast and are barely noticeable).

Hoping this is a software fix after just spending two days on re-installing everything I need. :/

I’ll have to experiment with it more when I get home from work tonight. When I fiddled with it this morning before I left, I should have tried it with a black desktop like you. Probably why I didn’t notice anything in the window corners, duh!
 
Comment

PieTunes

Contributor
May 6, 2016
763
1,104
San Diego, CA
The white lines seem to be limited to the desktop, not any active window. Whether a solid color or an image.
That was something I also noticed, it never happens in an active window, but in the background, namely the desktop. I don’t think I’ve seen it happen in any inactive windows or apps, just the desktop.
 
Comment

quagmire

macrumors 604
Apr 19, 2004
6,563
1,584
I am seeing the occasional white line pop up on my machine as well. I am fairly confident it is a software issue that will need to be fixed in an update which might be Big Sur at this point unless Apple does another supplemental update for the 2020 iMac.
 
  • Like
Reactions: PieTunes
Comment

kkh

macrumors regular
Aug 22, 2020
206
141
I’ll have to experiment with it more when I get home from work tonight. When I fiddled with it this morning before I left, I should have tried it with a black desktop like you. Probably why I didn’t notice anything in the window corners, duh!
Took me a while to notice. And as you move windows (or take screen shots, actually) the corners render correctly or incorrectly, seemingly based on the window positioning. It's almost like: if a window does not line up just so (imagining this could be a power of two type of lining up thing in the frame buffer) you see it. The flickering on/off can be very noticeable in the System Preferences window as you go between different settings and the window automatically resizes.
 
  • Like
Reactions: PieTunes
Comment

kkh

macrumors regular
Aug 22, 2020
206
141
Also tried setting Resolution to the various Scaled modes. No difference.
 
Comment

kkh

macrumors regular
Aug 22, 2020
206
141
So far I have tried the following. No difference. The problem persists.

• Different desktop images.
• Dynamic and still desktop images.
• Solid colors (the problem is actually the most obvious on solid black).
• Resolution set to Default or any of the Scaled resolutions.
• Automatic brightness adjustment on/off.
• True Tone on/off.
• Night shift on/off.
• The various Accessibility > Display options.
 
  • Like
Reactions: PieTunes
Comment

kkh

macrumors regular
Aug 22, 2020
206
141
Here's a video of the flickering corner as I slowly move Mail up and down. Here you can see it clearly going between a version with correct alpha and no alpha. But sometimes, it is not on/off like this but you get random pixels flickering. Only limited to the rounded corner area. Sometimes accompanied with the fast white lines on the desktop.

 
Comment

PieTunes

Contributor
May 6, 2016
763
1,104
San Diego, CA
Here's a video of the flickering corner as I slowly move Mail up and down.

View attachment 946672
I can see that now. I’ll see if I can duplicate it at home tonight. Odds are it will.

Appreciate you taking the time to do such thorough testing! It definitely appears to be a driver or OS glitch. I just imagine if it were an actual hardware issue, it would be more prominent in just about anywhere the screen is redrawn, and especially during GPU intensive situations.
 
Comment

kkh

macrumors regular
Aug 22, 2020
206
141
I can see that now. I’ll see if I can duplicate it at home tonight. Odds are it will.

Appreciate you taking the time to do such thorough testing! It definitely appears to be a driver or OS glitch. I just imagine if it were an actual hardware issue, it would be more prominent in just about anywhere the screen is redrawn, and especially during GPU intensive situations.

Curious to hear if the same is happening on yours.

It definitely looks like a driver or macOS glitch to me. I had hardware issues with another AMD card many years ago and it was pretty obvious because it went from full screen glitches in any app or situation to outright freezes.

This is obviously an iMac-specific card from AMD but I was reading about Windows users having driver issues with another 5000 series card from AMD (I think it's the RX 5### XT) and it took AMD forever to fix it, it looks like.

Because it seems to be this specific, I was also wondering if the macOS pre-installation done at the factory in itself is somehow corrupted.
 
Comment

torifile

macrumors regular
Original poster
Aug 10, 2020
141
127
There’s lots of evidence that this is a software bug. The biggest, IMHO, is that it only affects inactive windows. Hardware most likely wouldn’t differentiate that.

Like I said, I’ve just installed boot camp/windows 10 and I’ll see if the issues occur there. I’ve also got a USB-C to DisplayPort cable coming and I’ll hook up my 1440p display and see if it happens on that display.

it’s so fleeting, I might not be able to notice it even if it does happen but it’s worth a try.
 
Comment

costica1234

macrumors regular
May 21, 2013
149
100
London
Here's a video of the flickering corner as I slowly move Mail up and down. Here you can see it clearly going between a version with correct alpha and no alpha. But sometimes, it is not on/off like this but you get random pixels flickering. Only limited to the rounded corner area. Sometimes accompanied with the fast white lines on the desktop.

View attachment 946672
Was your iMac running on iGPU or on 5700 XT? I wouldn't blame the dGPU if this issue also happens while on integrated graphics.
 
Comment
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.