User profile for user: Grif_
Grif_ Author
User level: Level 1
28 points

Mac Studio M1 Ultra External Monitor Flickering

So tired of this....

Before anyone suggests that I read this or check that or change cable.... That has all been tried to death.


Apple M1 Macs have an issue with external monitor flickering. Period. Every OS update I wait in the hope that it gets fixed. Nope... Just did the update today and it flickered within about 2 hours.


In my situation I have 2 external BenQ monitors, 1 is 4k 32" PD3205U and the other (flipped sideways) is a 27" 1080p PD275Q.


The 32" is connected via a good HDMI cable and the 27" via a thunderbolt cable. Yes, I have tried MANY different cables)


I have a couple of external SSD enclosures in a Raid0 and another external SSD for backups. USB-C to DAC, and one or two other connections. Whether they are connected or not does not affect this.


Periodically, the 32" starts to flicker, mildly at first, then it may increase or stop entirely.


When you look closely at the pixels while this is happening you can see that alternate vertical rows of pixels are shifting. Reminds of old CRT monitors. It can flicker quite dramatically sometimes.


From what I can tell, this is NOT a 3rd Party hardware issue (cable or monitor). The issue usually happens when I am working in Photoshop or Illustrator and I am in the finder which usually consists of 2-3 large windows. The flickering comes out of nowhere. If I tab back to Photoshop the flickering may stop. Or, may not be as bad. Cycle through various apps and it usually changes. To me, the Finder is affecting this, or some part of the OS that is translating to the display.


BenQ have a page dedicated to the issue: https://www.benq.com/en-us/knowledge-center/knowledge/how-to-fix-mac-m1-m2-external-monitor-flicker.html


None of their suggestions nor anyone else have helped. There are tons of posts everywhere from Reddit to Macrumours to here that all raise the same issue (for the most part). Still.... no fix or no acknowledgement from Apple. Everyone says to change the cable or whatnot but it seems the issue persists for most of us.


I've been an avid Mac user since 1990 so I have an idea of how to troubleshoot these issues.


If anyone can give me any insight on how to resolve this I would be eternally grateful.


The odd thing is it tends to happen when I get very busy! Maybe it's picking up on my karma....



Mac Studio (2022)

Posted on Mar 26, 2024 11:46 AM

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13 replies
User profile for user: Grif_
Grif_ Author
User level: Level 1
28 points

Apr 23, 2024 3:42 AM in response to Grif_

Steps taken so far


Replaced cables



  1. .5M HDMI Ultra High Speed - Ubluker 10k 8k 4k HDMI 2.1 Cable 0.5M, Certified Ultra High Speed HDMI Cable 4K 120Hz 144Hz 8K60Hz 48Gbps ARC eARC Dolby Atmos HDCP2.3 Compatible Mac RTX4090 PC HDTV PS5 Xbox  https://www.amazon.es/dp/B09ZRPJZDL?ref=ppx_yo2ov_dt_b_product_details&th=1
  2. .3M Thunderbolt 4 - Angusplay Thunderbolt 4 USB C Cable 0.3M, USB4 40Gbps Cable, 100W 8K 60Hz Video TB4 Cable Compatible with Thunderbolt 4/3, USB4/3, Type C, for iPhone 15/15 Pro Max Mac MacBook Pro, eGPU External SSD https://www.amazon.es/dp/B0CNGS6576?ref=ppx_yo2ov_dt_b_product_details&th=1


Note, I already had several TB4 rated cables .5M but I thought I’d try a shorter one.


Peripherals

  • Thunderbolt/USB-C
  • Monitor Connections are direct to rear TB4 ports
  • 2 x external NVMe SSD Drives TB3 (Striped)
  • 1 x Samsung t5 SSD


USB-A

  • DAC


Tried the following


  • Restart Mac Studio - Flickering picks up where it left off
  • Disconnect Power to monitor - Flickering picks up where it left off
  • Create a new user - Flickering picks up where it left off
  • Change display resolution - No change to flickering
  • Change display Refresh Rate - No change to flickering
  • Toggle HDR (usually off) - no change to flickering
  • Night Shift - set to off
  • Display Pilot (BenQ) - ICC Sync on/off - no change
  • Changed HDMi cable to the .3M TB4 cable. - Flickering stopped - for now. 


Observations

  • The flickering starts mildly and gets progressively worse, then… eventually just fades off.
  • If you look at the closeup the flickering seems to manifest as vertical lines



Let’s see how I get on with the TB4 cable


https://youtu.be/buOp33e97M8

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User profile for user: Grant Bennet-Alder
Grant Bennet-Alder
User level: Level 10
127,081 points

Apr 18, 2024 8:01 AM in response to shtl2

<<. Lowered the resolution to 2560x1440 so I can read texts. >>


the "approved method" to obtain readability of TEXT is to use settings for Scaled TEXT "looks like" (larger/smaller) in the displays preferences, NOT lower overall resolution. This scales ONLY TEXT being displayed, and leaves the graphics at full resolution so you can enjoy the resolution you paid for when displaying graphics.


...


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User profile for user: Grant Bennet-Alder
Grant Bennet-Alder
User level: Level 10
127,081 points

Mar 26, 2024 2:33 PM in response to Grif_

<<. Before anyone suggests that I read this or check that or change cable.... That has all been tried to death. >>


<< The 32" is connected via a good HDMI cable. >.


There sure are a lot of crappy HDMI cable out there. What you did NOT state is that the HDMI cable you are using is one of these:


HDMI cables you want for HDMI-only Displays (higher resolutions than 720p TV sets) are marked as Certified with an anti-counterfeiting tag and are labeled:


"Premium High Speed HDMI cable" or that + "with Ethernet" --OR--

"Ultra High Speed HDMI cable" or that + "48G"


Cables with No Certification tags are good for your standard 720p TV set, and not much more.


HDMI was invented for HD TV sets. it works great at its original resolution of 720i or 720p. At higher resolutions, it quickly develops issues that are complex to solve, and the cables and adapters required to solve are NOT intuitive.




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User profile for user: Grant Bennet-Alder
Grant Bennet-Alder
User level: Level 10
127,081 points

Mar 26, 2024 2:37 PM in response to Grif_

<< the 27" via a thunderbolt cable. >>


To use a thunderBolt cable, the cable must be marked with the Thunderbolt symbol indicating it is certified cable. For use with displays at high resolutions, it must be shorter than 0.8 meters for Apple cables, shorter than 0.5 meters for brand-X cables.


<< Everyone says to change the cable or whatnot but it seems the issue persists for most of us. >>


yes but -- its not that you need a replacement cable, you need an ADEQUATE cable.

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User profile for user: Grif_
Grif_ Author
User level: Level 1
28 points

Mar 28, 2024 3:37 AM in response to Grant Bennet-Alder

Thanks for your response Grant. Appreciate your time.


The HDMi cable is what shipped with the monitor. HDMi 2.1 48Gbps. Probably should have stated more clearly, that this happens whether the monitor is connected via HDMi or Thunderbolt (licensed) cable.


While the flickering is happening I've switched cables and the flickering still appears so it feels like the issue is coming from the Mac Studio and has little to do with cable or monitor.

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User profile for user: shtl2
shtl2
User level: Level 1
8 points

Apr 17, 2024 10:31 AM in response to Grif_

Hello. Have some odd flickering since a few days, like old graphic card bug. Especially when working in c4d, the viewport starts flicker, stromboscop style. Very bad for my eyes. Certainly not good for the graphic card. Apple macstudio m1 ultra 2022, Apple Studio Display 27p, Sonoma 14.4.1


Bad driver ?

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User profile for user: shtl2
shtl2
User level: Level 1
8 points

Apr 18, 2024 7:37 AM in response to Grant Bennet-Alder

Hello

For the display, Using the factory cables (Thunderbolt3).

Lowered the resolution to 2560x1440 so I can read texts. Preset Apple Display (P3-600 nits).


I have 1 USB-C hardrive connected to the Apple Display.


I do have an USB 3 hub/dock connected to macstudio back ports, to connect 1 keybord (previous apple extended) and 2 external USB hard-drives.

And a Wacom tablet connected to the other USB back port.

Finally 2 mini usb 3 / USB-C hard-drives disks.


Indeed at each OS update I have to disconnect the USB Hub at start-up or it goes in repair mode.

But until Sonoma I didn't have those glitches/flickers. If it is connected ?!




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User profile for user: Grant Bennet-Alder
Grant Bennet-Alder
User level: Level 10
127,081 points

Apr 18, 2024 7:56 AM in response to shtl2

all USB-C shaped ports on the Mac Studio MAX processor are Thunderbolt ports.


The cable you have -- is it no longer that 0.8 meters for a genuine Apple ThunderBolt cable with the Thunderbolt trademark symbol on the cable? or no longer than 0.5 meters for a Brand-X Thunderbolt cable with trademark?


At 60 Hz refresh rate, the 5K Apple Studio Display consumes 25.92 G bits/sec of the nominal 40 G bits/sec Thunderbolt cable it is connected to. Practical limitations suggest it real capacity is more like 32 G bits/sec, so once you connect the display, it can not support an additional DRIVE. You should NOT be connecting a drive to that same port, except maybe a slow, rotating magnetic backup drive. Connect as many slower peripherals as you like, their sustained data needs are negligible.

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User profile for user: Grant Bennet-Alder
Grant Bennet-Alder
User level: Level 10
127,081 points

Apr 23, 2024 7:15 AM in response to Grif_

Grif_


Although cable selection is by far the most frequent problem, you appear to have eliminated cables as an issue.


Next on the list is Variable refresh rate settings. When variable refresh rates are described, most users hear that the refresh rate could go even HIGHER than nominal under certain conditions. They appear to ignore the other half -- that your refresh rates could go far LOWER than nominal, and if you are sensitive to it, could produce flicking in the process.


To test, be sure you have selected a high FIXED refresh rate.


--------

On a regular horizontally-oriented display, Only the display itself -- not ANY other component in the process -- knows anything about Vertical. the display is made up of a huge Stack of Horizontal slices. Only when the are exactly the right length, do you "accidentally" get Vertical features.


Problems with Vertical artifacts are almost always caused by problems inside the display itself.

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Mac Studio M1 Ultra External Monitor Flickering

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