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

What do these monitors have in common? Are they all VA? Do all of them work at the edge of their parameters? All of them are lower end equipment? Who is the display manufacturer? All 4K? My PHILIPS works flowless while upscaling. Were are monitors really ready for full 4K load (manufacturer lied they are really 4K)?

The Acer has been added to the list. :-))

Acer CB281HK

LG 32UN500 

Dell P27S21Q 

LG 27UL600-W Phillips PHL288B6

PHILIPS 328E

Dell S3221QS

LG 27GL650F-B 

ASUS MG28U 4K 

DELL U2421HE

DELL U2421HE.

Samsung U32R59

Dell S2817Q 

Dell U2718Q

LG 32UN650 4K

Dell U3818DW

Dell P2715Q. 

LG 24MK600M

Samsung LU28E590DS/ZA 28" 

Samsung R32R59x 

HP Pavilion 23xw 

LG 24MK600M

BenQ PD2700U

LG 29UB67

AOC 2879VF

PHILIPS 328E 

4k 32UL950-W.

LG 27GL650F-B

MSI MAG321CURV 4k

LG 24MP59G-P

Samsung LF24T350FHLXZX

ASUS PA248QV,

BenQ PD2700U

BenQ EL2870U

AOC Q2963P

I have been through various things with Apple support on the phone and the next thing I have been asked to try is a complete clean install of Mac OS and then to run the Mini for a while without installing anything on it to see if the issue occurs. I am assuming someone else has tried this already - if so did it achieve anything?

JJC138,

I think you were right not to waste any money on Dell's adapters, I have the same monitor and the issue happens even over native HDMI so I don't see what a Dell USB-C adapter is going to do. I suspect Dell are confusing this particular flickering issue (the vertical lines in dark areas) with the full screen flickering/blanking, as they have a web page up for another monitor model with those adapters as the recommendation.

I've been able to replicate the vertical lines/dark areas flickering problem on my Macbook 2015 on both High Sierra and Big Sur, so this is either a long standing problem with MacOS or indeed the monitor just doesn't play nice with the Mac in general.

Bit disappointing as I've been a long time Windows user where generally you can plug in any old hardware and it works fine, for now my M1 Mini has been abandoned as I have no desire to spend any more time or money trying to resolve this, which is a shame as its a lovely little machine.

Yeah, I'm in the IT field and had serious doubt about their suggestion of buying an adapter. I tried using USB-C to HDMI cable, HDMI-HDMI cable, and using a USBC-HDMI adapter. Also found a guy's suggestion on Reddit to force the M1 Mini into RGB (the default color profile is YPbPr on my Dell), but that didn't help either.

I'm the same way, came over from the Windows side saw that Dell on Slickdeals for like $330 shipped and bought it thinking it'd be the perfect high res monitor for my M1 mini, boy was I wrong.

I should also mention that Dell sent me an e-mail asking me to review my purchase, so I gave an honest review (1 star) and in the review, I detailed the issues and said if you're using a Mac Mini M1 that you should not buy this monitor and they "moderated" my review (basically rejected it). I wasn't very happy about that either.

if all those monitors work with other hardware flawlessly (which they do) both old macs and pcs it is not the monitor that is the problem it is the M1 chip itself. No standards have been changed and the M1 should be compatible with all monitors.

the best thing that can be done is a list compiled of working monitors or a recall on the entire M1 lineup especially the Mac mini which it affects the most since there is no internal screen.

I ended up returning the Benq for 2x LG UL550 not had a problem since for a few months now. Only issue Is if I don’t wake the screen manually before the Mac mini it forgets its resolution.

has anyone noticed that in system report the Mac mini is actually outputting 5k to a 4K screen ? I wonder if the scaling is an issue since the monitor is working hard downscaling.

I posted in this thread earlier about having the issues with the HP Pavilion 23xw on my M1 MacBook Pro. I’ve since upgraded to the LG UN850-W 27” 4K monitor and have NOT had any flickering/vertical lines. In fact, as far as I can tell (and I am picky about these things), there are no graphical issues of any kind using this monitor. YMMV, but this appears to be one of the monitors that works with the M1.

There is a formula that will allow us to know which screens work with M1 it just needs to be found. I thought it was any IPS panel but it’s not , I think it’s something to do with the chipset used in the monitor that drives the panel as quite a lot of the LG screens work in the newer range but a few don’t. That would suggest the screens driver chipset is probably the same on many LG monitors

I can confirm that the Samsung LU28R550UQUXEN is also affected. It's fine most of the time but there are some windows or content it does not like that flicker like crazy. It might be more usable than other monitors as it took me a couple weeks of use before I actually noticed the issue for the first time.

I just got the LG UN850-W 27” 4K - no flickering, vertical lines or other issues so far. BUT - HDR is not working! Enabling HDR gives me washed out colors and when I try to play an HDR video (recorded via iPhone), the window goes black.

Yeah, I noticed that too. I don't believe that it is an M1 issue though, as you see reports of the same thing from Intel Mac users (which is not the case for the flickering/vertical lines). For me I don't have much need for HDR so I don't really care. The display looks great without it -- *almost* as nice as the 5K iMac.

Hello, I believe I have found a "fix", it's more like a workaround. This issue happens because the m1 defaults its video output to ypbpr, instead of RGB. You can edit the com.apple.windowserver.displays.plist file to force RGB output. This will fix the problem of vertical lines, image retention and flickering.

This video explains it really well https://youtu.be/Z1EqH3fd0V4

Sorry to hear that. Note that the output defaults back to ypbpr when changing any of the display settings within system preferences. Also, the issue can persist for a while even when unplugging the mac mini or when using another input. So maybe you were experiencing some leftover flickering?

What has worked for me is to reduce the native resolution of the monitor to 2560 x 1440, I no longer have 4k res but at least I can work without flickering. BenQ el2870u, hdmi - hdmi Ugreen 2.1 Cable 8k / 60Hz.

I think that monitors with IPS panel work and monitors with TN panel have troubles, maybe because of their faster response time (1 ms instead of 4-5 ms). Anyway, I replaced my BenQ el2870u by a new HP U28 4K HDR with IPS and now I can finally enjoy the new mac.