MacStudio (M1) Display Sync Issues

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Level 1

15 points

MacStudio (M1) Display Sync Issues

Here's the problem, and yes I'm aware that it, and similar, are pretty common but nobody has provided any answers. Is Apple paying attention?

I run a MacStudio M1 Max, 64GB memory, 2TB HDD. Sequoia 15.5. 2 x Dell S3221QS displays. Displays set to my optimal viewing, 2560x1440. Refresh rate set to "variable" (40-60 Hz). Connected with 8K cables to the display port input on the monitor, and two of the four Thunderbolt ports on the rear of the Studio. I've made many OS updates in the past months, all the same results.

When I first upgraded from a 2018 MacMini, monitors would flicker all the time until I switched the refresh rate from 60 Hz fixed, to the variable as I noted. Now, I still get some flickering--monitor goes black, or starts to go on and off. It's more noticeable when an embedded video link on Safari plays, less so on Chrome.

When the same monitors, at the same settings with the same cables were used on two different 2018 MacMinis, there was NONE of this. No flicker or sync issue of any kind, ever. Soon as I moved to the studio, troubles. It's not the monitors, or the cables. I switched the ports too, same result. Thus I conclude it's not anything in my setup, it's something in the Studio. Also guessing its software/firmware, not hardware as the issues are inconsistent.

Guessing It's something in the system operating software for the Studio's built in GPU. Looking around the 'net I see plenty of people with this issue.

Anyone have a clue as to what's going on? A monitor like this with a good cable should be "plug and play" and not have any issues at all. Any ideas for a fix?

Mac Studio, macOS 15.5

Posted on Jun 1, 2025 12:19 PM

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Answer 1

mdsalemi Author

Level 1

15 points

Jun 2, 2025 07:45 AM in response to mdsalemi

I'm the author and I'm augmenting the question/problem above. One of the pieces of software I run is actually a suite of photo editing software by Topaz such as Gigapixel AI, Photo, etc. Running these sends my monitors crazy. I know for a fact, from having spoken with Topaz tech support that much of the processing done by their software is done by the computer's GPU not CPU. So, there's something with the OS software and the Studio's built in GPU as it didn't happen when the same software was running on the MacMini.

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Answer 2

mdsalemi Author

Level 1

15 points

Jun 3, 2025 07:54 AM in response to den.thed

I staggered the use of the ports, using (L to R) #1 and #3, instead of #3 and #4.

I changed all my settings to exactly as shown in the screen shot: Stage Manager, Tiling and Mission Control settings disabled.

No change.

I loaded a photo into Topaz Photo, and immediately the monitor that had the Topaz window started blinking on and off.

As I had mentioned in my followup, I know that processing by Topaz software uses the GPU not CPU, thus something in certain software, such as Topaz, or in the case of videos embedded into web pages starts a sync issue with the monitor.

There's very little control over anything on the display. You choose the resolution (in my case I've chosen 2560 x 1440, well below the monitor and system capabilities). You choose the color profile, in my case Dell S3221QS, but profile should have nothing to do with sync. You choose rotation, in my case standard. There's a setting for when connected to TV which is not applicable. You have advanced settings, and choosing that tab only gives you options for connecting to a nearby Mac or iPad, again, not applicable. Then the only remaining choice is Refresh Rate. When I had this same dual monitor setup on my prior MacMini 2018, this was set to 60Hz, the spec of the monitor. If I do that, both monitors flicker on and off. The only partially acceptable solution is Variable (40-60 Hz) but as noted, certain things that are using the GPU send the monitor(s) out of sync.

I'm at a loss and out of ideas.

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Answer 3

mdsalemi Author

Level 1

15 points

Jun 10, 2025 06:54 AM in response to den.thed

None of those changes had any effect. It does not matter what Thunderbolt ports the monitors are plugged into. It does not matter what those other setting are either.

I can tell you this for certain--ZOOM is unusable for me. As soon as I go into the zoom workspace the monitors (which may have been fine for the day) start going black on and off.

Again in researching this many others have the problem. I don't know what others have discovered in any testing. I'm pretty stable unless an embedded video in a web page is shown. Certain web pages worse than others. Safari worse than Chrome. Zoom is the worst.

Something causes a sync issue.

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