Level 1

21 points

M1 Mini issue with LG 27" 5K Monitor

I have a new M1 Mini running the LG 5K monitor from they Apple store. The monitor is recognized with the 5120 x 2880 resolution spec on boot or monitor reset (unplug and reinsert thunderbolt cable), but invariably falls back to a 3840 x 2160 resolution when the monitor goes into screen saver or sleep.

Three different thunderbolt cables have be used, a second LG Monitor tried, and have tried both Thunderbolt ports on the mini. A replacement Mac mini seems to be the last resort, but I feel this may be a bigger issue affecting others, and that a replacement will not fix this.

Is anyone running this monitor with Big Sur or ideally with the M1 Mini?

Posted on Dec 11, 2020 5:36 PM

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Chris Wilhoite

Level 1

9 points

Posted on Jan 17, 2021 6:39 PM

thoughts,

I called Apple Saturday and started a case. Talked to a senior tech person for a while. Went over everything. Told her about these threads in the forum. She had me set the energy saver to never. Thinking that this would push it to occur. The interesting thing is since changing it, it has never occurred. Makes me think that going into sleep may be what is causing it. WHY, I do not know.

I did see that there are 3 threads about this and on one someone mentioned they could make it happen by setting a hot corner to sleep monitor.

She also wanted me to try using the USB-C cable supplied by LG and see if it still happens. Have not tried that yet as I am seeing how long it will go without messing up by sleeping monitor being set to never.

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100 replies

Jan 16, 2021 7:45 AM in response to K9x3

Add me to the list of those having a new M1 Mac Mini and new LG 27" Ultrafine monitor having a shift near the center of the screen. Really annoying and would like to find out why. I am running the update 11.1 and using the supplied Thunderbolt cable. Screen shot does not show it. Will follow this thread and put in a report to Apple. Have not tried the 'hot corner' idea but sounds like an easy work around until the real problem is solved. After reading all the posts, its really hard to discern what is causing this, Monitor or Mini or cables or what

Jan 16, 2021 10:18 AM in response to K9x3

K9x3, have you had the problem with both the Thunderbolt and USB-C supplied cables that were included with the LG Ultrafine 27" monitor? And you are saying you are still having the issue after the 2nd one form LG?

Jan 16, 2021 6:27 PM in response to K9x3

I'm using the same input for the USB-C (I believe the others are only to be used as a hub but I could be wrong). Everything functions just as it should with the thunderbolt 3 cable (camera, speakers,charging and resolution). The only difference I could possibly see happening using the USB-C is lower cap on speed if using a thunderbolt 3 specific hard drive connected to the hub. Other than that I see no need for the thunderbolt 3 cable over USB-C. I'm really hoping I'm onto something since I haven't seen the pixel shift happen yet. Could really just be a defect in the thunderbolt cable spec when being used for a monitor.

dre1138

Level 1

4 points

Jan 18, 2021 8:30 AM in response to Chris Wilhoite

Yes, sleeping the monitor by moving to a hot corner can either cause or fix the "band of shifted pixels" problem. Just reproduced this and saw it at my login screen. I didn't log in and waited for the screen to go black again. Then woke the machine and the problem did not show.

On a different note, when I go to System Preference > Desktop & Screen Saver, the settings area for Screen Saver is now empty! This is fixed by a reboot.

K9x3 Author

Level 1

21 points

Jan 18, 2021 11:24 AM in response to Ross Ellingson

Thank you Chris, I'll give it a go. I've had the pixel shift issue a number of times already today. If this works, I'll let you know. Heres some info on the 5K monitor resolution that is interesting. The apple method sends two streams of the same image to get the 5K resolution. https://en.wikipedia.org/wiki/5K_resolution

K9x3 Author

Level 1

21 points

Jan 18, 2021 4:27 PM in response to Ross Ellingson

Interesting -- so when you go to About this Mac and select the Displays Tab, does it show the monitor as 27" (5120 x 2880)? If so, yours is working differently than mine with that cable. When I used the cable and checked the Display in About this Mac, mine had stepped back to 3840 x 2160, which is 4K.

For whatever reason, Displays under System Preferences doesn't show you the resolution of the monitor, but I see you have it as a scaling option. What is your system configuration -- Is this the Intel MacBook Pro running Catalina? If so, you likely have a dedicated graphics card which I don't with the M1 Mini.

Hopefully you've found your solution. The USB-C cable that came with the monitor is not an option for me.

Thanks.....

K9x3 Author

Level 1

21 points

Jan 18, 2021 4:36 PM in response to usb_drive

Thank You USB-Drive, that helps a lot. I understood the largest difference in the first and second gen monitors was the power supply being larger in the second gen monitors. Do you have any insight on how to determine the firmware version of the monitor. I haven't been able to get hold of the right person at LG and never have been able to determine what the latest firmware version is. LG Screen Manager did nothing for me and didn't recognize the monitor.

Jan 18, 2021 5:15 PM in response to K9x3

I have also called LG when I first encountered this problem and found the forums. Its unbelievable a company like LG has such horrible support. They were completely clueless and told me to "send it in". The person who was on the phone wasn't even aware the display has no buttons on it...Note to self when dealing with LG products. Just return or troubleshoot yourself.

Jan 18, 2021 5:23 PM in response to K9x3

Running Catalina, late 2019 MBP 16" with radeon graphics. About this Mac shows 5k resolution as well. So I guess I'm lucking Gen 2 supports 5k with USB-C. You said you're stuck with 4k if using USB-C. Did you see the pixel shift happen though?

Jan 18, 2021 5:43 PM in response to Ross Ellingson

Wow, this is all so interesting and well disheartening at the same time. I am currently using the LG supplies USB-C cable and have not had the shift happen. My LG only shows 3840 x 2160 as top resolution, so I am guessing I have a first gen. monitor although it was purchased from Apple a month ago. Not sure what to think about all this. Get an Intel Mac Mini replacement, live with the hot corner fix with the Thunderbolt cable, wait to see if Apple fixes in an update?

I believe usb_drive said in one of his posts he thought Apple was fixing a few video things in 11.3, I think.

Being an early adopter does have its problems

K9x3 Author

Level 1

21 points

Jan 27, 2021 5:41 AM in response to CharlesHsu

Thank You Charles. It is helpful ton find other examples where this is not a M1 or Big Sur issue. Unfortunately the LG screen manager app does not work on the M1 Mini. so I have no apparent way of determining my firmware version on the monitor. I have even looked through System Report and could not find a corollary to this firmware version.

Regards...

Feb 4, 2021 12:04 PM in response to dre1138

Warning macOS 11.2 has a lot of problems and disables OWC computing‘s soft raid driver. It is very very difficult to downgrade an OS on an M1 Apple silicone Mac. I highly recommend not upgrading. I would’ve mentioned it before but I’ve been working on restoring this machine for over 24 hours now.

K9x3 Author

Level 1

21 points

Feb 9, 2021 9:19 AM in response to Melankani

I'm trying to open up a dialogue with LG regarding the matter, but starting with Tier 2 or even tier 3 support. I requested an Engineer. Previous attempts got nowhere. I'll update the forum if I get anywhere with them.

Feb 9, 2021 12:10 PM in response to K9x3

Just to add fuel to the fire, the integrated webcam in my LG 27MD5KL-B appears to have failed. It doesn't appear in any capable application on my M1 Macbook Air (or 16" Intel Macbook Pro). LG wants me to send the monitor back. Yippie, like that is going to help me at work. Of course there isn't a way to factory reset this monitor. Thanks, LG.

Feb 11, 2021 8:36 AM in response to K9x3

Hey there,

Just wanted to chime in and report that I also have the pixel shift issue with the LG 27” UltraFine 5K display (27MD5KL-B) with my MacBook Pro (13-inch, M1, 2020). Like the others have shared here, the issue happens in the centre of the screen and is temporarily fixed after refreshing the display, but roughly every ten or so times the monitor is woken up, the issue persists again. Unfortunately, it’s still an issue with the latest version of macOS (11.2.1).

I’ll keep an eye on this thread and will report back if and when the issue is fixed for me.

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M1 Mini issue with LG 27" 5K Monitor