Mac Mini (M1) 2020, LG UHD monitor flickers on dark colours.

After seeing a video of the extent of the issue on other monitors, I would review my rating of LU28R550UQUXEN as "mostly working". As I said it took several week not notice a flickering issue. I've seen only seen a dark screen flickering a couple times (and I'm mostly using dark mode). I found this subject because I do have an annoying recurring flickering issue when using in OBS Virtual Cam preview when displayed in the target app but I'm now thinking it could be software related and might have nothing to do with the discussed issue.

mine are both IPS panels and Benq's are quite good on their price range. my displays are working perfectly with my windows laptop and MBPs but not with my new mac mini M1. so the problem is with the mac mini M1.

Yes I agree def with Mac mini but it seems to have a compatibility issue with some monitors - for me it was just easier to replace the monitor as there is not alternative to the M1 mini that suits my needs.

but there are people who are using the same displays with no problem at all. I'll see with the new logic board if this will still be persistent. if it does then it's compatibility indeed and they need to do some fundamental changes on their hardware/OS.

Well, I think every owner of *two* different M1 Macs who has experienced this issue could reproduce it on both computers - I haven't read a single posting saying only one of the M1 Macs was affected.

I also haven't read of a "successful" replacement, so I think it's not some defective units, but rather a design issue with the M1 SoC.

I hope the board replacement fixes the problem for you, but I have doubts. If it does, it could mean your problem was either some different issue altogether or Apple has secretly released a new hardware revision.

I will definitely be updating the community regarding this replacement. I am hopeful only if the replacement logic board is of a different version/build. If it is just the same, and if the problem is persistent with mac mini M1, then BenQ should also update their website as they marked their displays as M1-compatible/supported. Perhaps we can compile a list of displays with "compatibility" issues with mac mini M1, including fixes (if there are).

Apologies for the incoming rant but I just have to express how frustrated and annoyed I am with Apple with this issue.

I decided tonight to spend some time documenting everything I've tried, take video/pictures of the flickering as it was happening, and then contact Apple support in the hope I might be able to have a reasonable conversation with someone and at least add another voice in the hope they can look into it.

As it turns out, none of the advisors were interested in looking at the information I had put together - they had me try the usual safe mode, power off for 30 secs etc... after which the advisor was about to arrange a return of the mac mini for review/replacement. Then a "senior" advisor stepped in and proceeded to fob me off, saying that because a second (totally different) monitor I have works, then it has to be my 4K monitor that at fault, despite me referencing this thread and everyone else here having the same issue, and the fact it works in Windows 100% with no issues. I got a load of copy and paste replies, and then was denied the replacement that the previous advisor had started to arrange! He wasn't interested in the slightest and was clearly following a script.

By far the worst support contact I've ever had with Apple. Since when did monitors work with one operating system properly, and not another? I've never seen it in 30+ years of using and building computers. Displayport and HDMI are standards, surely if an OS and GPU conform to those standards, it should work. This is a Mac/M1 problem in my opinion and Apple are just burying their heads in the sand, as usual.

I hope the rest of you can reach some sort of conclusion to this eventually, however for me the M1 Mac is going, I've spent far too much time trying to fix this. It's a shame I now have a rather bitter taste in my mouth from Apple support, my opinion of them has taken a sharp downwards turn tonight :(

Cheers

Re-open a case again and again and again, like what I did until I was able to talk to a decent senior advisor. Initially, the AASP assigned to me gave a "properly working device" diagnosis on my unit but I vehemently challenged the diagnosis and elevated the concern to a senior advisor again and again.

Have your unit inspected first and when you have the unit delivered to the AASP, perhaps the "Geniuses" there would make some sense and I think it might be easier to elevate the claims while they have the unit at hand. Specify the model of the displays you are using, etc; give them a copy of the videos you have.

I have the same issue with my M1 Mac Mini and my ASUS VP28U 4K display. In my case there is only this 1 display.

I tried it connected directly via HDMI (and yes with short/high quality cable) and I also tried it via OWC TB dock (via Mini Display Port to Display Port, and yes and yes with a short/high quality cable) and it occurs both ways.

The issue occurs for me most often after visiting "certain websites" (not all websites, but the ones that have the issue are repeatable). The flickering will occur and then it will slowly fade away and then it stops flickering.

By comparison, if I connect my 2018 Intel Mac Mini to all of the exact same hardware I mentioned above then there is no hint of flickering and everything works without issue.

I'm putting this ball in Apple's court and I think they need to take ownership of it. Its real Apple.

I have a M1 Mac mini bought July 2021, and a Asus VP28U monitor and have started experiencing the vertical lines, particularly noticeable in dark mode. I can readily replicate the problem just opening a PNG file in Quicklook - sound like it's different conditions for different people. Switching out the HDMI cable did not resolve the issue (tried about 4 cables of various qualities). Fortunately the Asus also has DisplayPort input so I bought a Comsol USB3 to DP cable and hooked it up. The Mac happily serves up 4k@60hz and all the lines, flicker and ghosting is gone. For me I'm pointing my finger at something dodgy going on in the HDMI implementation. Hopefully new firmware or OS will fix it up one day, but having a DisplayPort alternative has me solved for today.

It would be interesting to know if it also works with BENQ EL2870U. I had this monitor before and it was flackering with M1, and I have never tried to use the display port input. I have replaced this monitor with another one to solve the issue, so I can not test it any longer. I believe if it works it could help many people.

The display port makes no difference, you will find the flickering will start on different shades of dark grey to the shades of grey that triggered the flickering on the HDMI. I had a BENQ EL2870U and tried all sorts for a month. In the end I swapped it out for a LG UL550W far more expensive but no issues since. This does not mean there was anything wrong with the BENQ , this is a compatibility issue with apple rushing to market the M1 and the standards have not been checked. Something has been missed somewhere.

Has anyone else noticed though that in about this Mac > system report > graphics displays > Resolution when a 4K monitor is connected is listed as 5120 x 2880 which is 5K? This means that the monitors are doing all the work downscaling to 4k. I remember when I had it set on 2k the flickering issue went on the benq. I think this has something to do with the problem there is no setting for 4K scaled output which looks like 2560 x 1440.

I have not found a way to send 4k to a 4k screen with scaling on a 27" monitor without text etc looking too small/too big. Windows 10 does this fine with ease but apple insists on doubling whatever the non retina resolution is. E.g on a iMac 22" its 1920x 1080 doubled which is exactly 4k 3840 x 2160 this is perfect if you own a 22" 4K monitor but if you own a 27" monitor apple is expecting you to connect a 27" 5k monitor which is double the correct scaling for that display base of 2560x1440. The industry standard for a 27" is 4k. 5k ones are $$$ and rare.

I have the same issue on M1 mini and Dell 4K. One dell is 27" and other one is 24", both 4K. The one has TB-DP connection and work flawlessly (this is 27"), the other is connected HDMI-HDMI (24") which has vertical lines flickering and picture disappearing for few seconds, which is very annoying.

I'm slowly considering asking official retail for replacement of M1, but this might not solve the problem at all. Main issue is that macs have only 1 year of warranty and this may expire before we will know if there will be any fix or not.

One thing I have found out that temporary helps is unplugging HDMI from mini and plugging it back. This will make monitor flicker free for few minutes. Also putting mac to sleep seems to worsen the problem, so it might be something wrong with sleep or display sync. Not sure as I do not have much time to dive deeper on this - this should be solved by Apple anyway.

Also if I go into system report I have this

 Displays:

DELL P2715Q:

  Resolution: 6016 x 3384

  UI Looks like: 3008 x 1692 @ 60.00Hz

  Main Display: Yes

  Mirror: Off

  Online: Yes

  Rotation: Supported

  Automatically Adjust Brightness: Yes

DELL P2415Q:

  Resolution: 5120x2880 (5K/UHD+ - Ultra High Definition Plus)

  UI Looks like: 2560 x 1440 @ 60.00Hz

  Mirror: Off

  Online: Yes

  Rotation: Supported

  Automatically Adjust Brightness: Yes

I would say a problem might be too high resolution set on HDMI as it doesn't have enough bandwidth to display it anyway.

Just an update on my own issues (flickering lines on dark areas of display, display recognition troubles, etc):

the MLB of my mac mini m1 16GB has been replaced, and the problem is still persistent! the certified tech saw it with his own two eyes. so I guess there is really a fundamental issue with the 16GB RAM/8-core GPU variant of M1. Time for Apple to own this one. I am now demanding for a refund and NOT for aa replacement. I'll just buy something else.