S3221QS, macOS, flicker, vertical lines, #2

Here's an example video of the flickering: https://www.youtube.com/watch?v=K2SIveZLjls
The only thing that caused the monitor to switch from flickering to non-flickering was that I clicked on a different window (off-screen), which changed the layout of how much dark/light content was on the screen, and where.

* Can you replicate the issue when running the Built-in Diagnostics? You can run the Built-in diagnostics only when the video cable is unplugged and the monitor is in self-test mode

* Can you replicate the issue on a PC running the supported Windows OS?
Dell monitor, Apple FAQ
None of the Dell D, E, G, P, S, SE, Alienware monitors have any macOS support from Dell. As a consideration to macOS users, on some of these monitors we did provide a firmware update that can be run from the macOS.

Built-in diagnostics are fine.  And I've only seen the flickering with my Mac, though I don't really use Windows much so it's hard to say for sure.

However, I did find another thread online indicating the same problem across a range of external displays with the Mac.

For now, I'm testing just selecting a different color profile (SD 170M-A) manually, using the GUI drop-down menu. If that fails, I suppose I could try the terminal-based stuff to dig deeper. I'll post my findings here, as it does take a while to encounter the flickering-inducing screen layouts.

For what it's worth, setting the color profile to SD 170M-A didn't really fix the problem. It maybe was a touch better, but not perfect.

I think the real problem here is that the S3221QS isn't that great at displaying high-res YPbPr content. And the Mac will default to using YPbPr over HDMI. One option is to use a USB-C to DisplayPort adapter, and macOS will send RGB data to the monitor. Alternatively, you can force macOS to default to RGB over HDMI for the monitor by following the steps here: https://gist.github.com/GetVladimir/c89a26df1806001543bef4c8d90cc2f8

Specifically:

1. Copy the ~/Library/Preferences/ByHost/com.apple.windowserver.displays.[GUID].plist to ~
2. cd ~
3. Run plutil -convert xml1 com.apple.windowserver.displays.[GUID].plist
4. Edit this file to add new LinkDescription sections as described
5. Run plutil -convert binary1 com.apple.windowserver.displays.[GUID].plist
6. Run plutil -lint com.apple.windowserver.displays.[GUID].plist
7. Copy this file back into ~/Library/Preferences/ByHost
8. Reboot
9. Confirm via the monitor OSD under "Color" that "Input Color Format" is "RGB"
10. Enjoy higher quality picture, and lack of flickering.

Hi,

I don't think YPbPr is the problem as I also tested using a USB-C to DisplayPort cable with RBG signal and the flickering issue persists, especially at certain grey levels. Changing the color profile won't solve the problem but might make the problem go away for the content you were watching previously as the displayed grey level for that content s different now. I can always see the flicker in the first 10s of https://www.youtube.com/watch?v=ACiyYOz0wsQ as the grey content changes a lot in the video. Note, you might need to watch the above video in full-screen mode to see the flickering.

I thought it was a compatibility issue between apple silicon and these reported flickering monitors as they're the case in many threads. However together with apple silicon also came the new Monterey OS and I noticed my old 2015 MacBook Pro with Intel chip also started to have the flickering issue with S3221QS with Montemery OS. It didn't have the flicker issue before the OS update as far as I can recall.

I had an S3220DGF(QHD 165Hz refresh rate) for a PC. I hooked that up with my M1 Pro Macbook and there's no flickering issue at all regardless of cable option and color profile. At the same time, connect the S3221QS to my PC and it doesn't have any flickering issue at all. So that worked out for me in some way.

Hopefully, the flickering issue will be solved by a Mac OS update or Dell firmware update eventually.

Ok, I have confirmed that switching to RGB mode does NOT "solve" the flickering problem.

Just like changing the color profile possibly decreased the chance of me "organically" encountering the flickering, changing to RGB mode perhaps had the same effect. But with the benefit of switching to a higher-quality picture. (The defaulting to YPbPr for HDMI-connected monitors seems non-ideal)

Here's a video of the screen clearly being in RGB mode, while entering the flickering mode (by moving the location of an off-camera window on the screen. And yes, this recording is from a Mac. I just happen to be on an RDP session to a Windows host at the time.

https://www.youtube.com/watch?v=5xDPRBHYwq0

I'm experiencing the same issue. Has this been solved?

Not that I'm aware of.  A non-trivial part of my day is spent rearranging windows on my screen to find something that doesn't trigger the bug. 

Your best bet is probably to stick to monitors that claim Mac compatibility.

@Miles15​ I am having the exact same issue and decided to try watching the video you mentioned!! By the sounds of things it is a common issue with these monitors. I tried attaching a video of mine but the file is too big. 

Hello All, 

Firstly, this monitor seems to be the most BANG for your buck... 32", 4K... Very nice monitor overall. 

I too was experiencing this same flickering/fine vertical line issues.  

Of note... There doesn't appear to be a problem at the full resolution of 3840 x 2160, at least for me , and my 2023 M2 Mac mini connected via HDMI. 

I think I found the actual problem... It seems like it has something to do with the default Dell Color Profile.  When I switch it to ANY other color profile... The monitor is completely stable in all situations. 

I hope this helps everyone out. 

T ;)