Mac Studio M1 Ultra External Monitor Flickering

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.

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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.

To be used for high-end displays on a Mac, it also needs to be one meter or shorter.

Recent versions of MacOS are ready the status provided by the display. Any transmit errors cause the link to disconnect or reduce the relation. cable longer than one meter tend to use too mush signal attenuation, and that shows up as errors.

<< Only happens on the BenQ 32", the other monitor is fine. >>

do you have another video source to swap in to use the BenQ display with?

consider scanning the manual for "on-screen display" settings (internal to the display). Some users have found that internal display settings for gaming interfere with their spreadsheets, for example.

Consider contacting BenQ for Assistance.

<<. 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.

I am happy to help. I have been studying this stuff, and had the limits mostly in my memory and a quick look-up away. So adding them to this discussion was not much heavy lifting.

What swapping Different (unspecified) display cables does, is hedge against BROKEN cables. These days Broken cables are rarely the issue. It's mostly cables that are too long, too low spec, or not certified (so not likely good enough quality to pass a certification test.)

The rapid jump in external display resolution to 4K and beyond requires far more precision in the cables, because those data rates are ferocious! Cables that worked with Windows, or with older systems, or with lower-resolutions sometimes just don't make the cut.

Apple-silicon Macs have taken a HUGE step forward in computer architecture by increasing the bandwidth to RAM memory, by almost an order of magnitude. That allows even faster fetching of display data, and stuff that used to 'get by' at slightly slower speeds no longer 'gets by' without generating errors.

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 ?!

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.

did you see this line in the original posting?

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

If Benq thought for a moment this was a problem that Apple caused by deviating from standards, they would have blurted out what they had found.

Apple-silicon Macs are unique in that they have the memory bandwidth to be relentless in sending data to the display. Display-makers may have 'gotten away with' slower data transfers in the past, but now that the data appears at top speed, it is becoming a problem.

A 0.5 Meter Thunderbolt cable SHOULD have worked error-free. I don't know what went wrong there. Perhaps that still ran into the festering BenQ issue.

An important distinctive feature of the Apple-silicon M-series Macs is their tremendous memory bandwidth, which is likely to be increasingly important as users find ways to use it all up and more. That bandwidth gives Apple-silicon Macs the ability to produce screen data streams that are completely relentless -- no dead times in between packets or screens to give peripherals time to recover.

As for BenQ, It sounds like older systems paused a little between packets and between screens, and BenQ had been counting on those little pauses, taking advantage of that extra time rather than meeting the EXACT specifications. Thus, a hardware change (no way to know how extensive) was required to eliminate the corner-cutting and bring it up to conformance with the exact spec. (Clearly if Apple were operating beyond the actual spec, BenQ would be protesting loudly about it.)

Regarding older Macs, what readers are generally finding is that more recent versions of MacOS are increasingly demanding in seeing NO transmit errors. if your older Macs are running older versions of macOS, they may not be complaining, simply because they are not checking so carefully.

<< 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.

Cables 'shipped in the box' are notorious for being 'lowest bidder' cables, and unless it has a certification tag attached, it still may not be up to the job.

When running at HDMI 2.1 speed and resolution, HDMI switches to a signaling method very similar to DisplayPort, which is limited to one meter maximum length.

<<. 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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