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 13, 2021 8:48 AM in response to K9x3

yes, this was an issue since Catalina. It happens on both monitors so I doubt it's a hardware issue.

The hot corner idea is great! I will try that out. I hate unplugging and replugging the monitor.

MEADEN

Level 1

15 points

Jan 18, 2021 4:33 PM in response to Ross Ellingson

Yeah, the second gen LG can support 5K over USB-C, the first gen could only do so over Thunderbolt.

May 10, 2021 12:45 AM in response to SCoupeville

I have the M1 Mac mini and the problem has been there since the get go.

Lower your expectations of the software updates because the problem gets worst after every update.

K9x3 Author

Level 1

21 points

Dec 12, 2020 4:09 PM in response to Douglas Holschuh

Thank you for the reply. While it's good to know someone else is experiencing the issue, it makes me wonder if replacing the M1 mini will fix it. II expect I will have to decide whether to use the LG monitor as a 4K monitor or send the mini back and wait for an M1 iMac. I tried contacting LG to ask what the latest firmware version is, but honestly, they are not very responsive. The LG screen manager software on the apple store is intended to show the version and update it, but it did not work on my M1 mini. This is the first time I've been less than impressed with Apple, and I don't want to buy into an intel iMac at this time. Best of luck, and if you learn anything, please let me know, and I'll do the same.

K9x3 Author

Level 1

21 points

Dec 24, 2020 7:09 PM in response to MEADEN

Meaden, did you ever resolve the issue with the section of the screen being off vertically by a few pixels. I still have the issue after replacing the monitor and the Big Sur patch. I no longer have a resolution issue anymore, just this same section in the monitor that is ocassionally off by a few pixels. Apple is sending me a replacement M1 Mini, but I'm not too confident it will resolve the issue.

K9x3 Author

Level 1

21 points

Dec 25, 2020 4:11 AM in response to MEADEN

Thanks for the response. I have the same thing going on and correct it the same way. Mine is always on the screen in the exact same place and width -- The right edge of my vertical section is aligns just left of the camera. Mac is sending me a new Mini, and I'll see if that corrects it. Because the second monitor is doing the same thing in the same spot, I don't believe it is a monitor issue.

Happy Holidays

Dec 28, 2020 8:40 AM in response to K9x3

How did you convince Apple to send you a replacement computer? I have exactly the same pixel shift problem with my Macbook Air 13". I suspect that it is an issue with the way the M1 graphics architecture works (the 5k displays are treated as two displays tiled together to get the higher resolution). I tried to explain this to an Applecare tech very nicely and she insisted that it was a monitor issue and she couldn't help. It ended with me saying "I'd hoped for some help but since you are useless, I'm giving up on you now, goodbye." Customer service nightmare. I wish I'd taken the option to answer the survey.

K9x3 Author

Level 1

21 points

Dec 28, 2020 10:16 AM in response to usb_drive

One other question, I presume you running the 5K monitor as an external display from your M1 MacBook Air. Is the pixel shift only seen on the 5K monitor?

I can video the shift, but any screenshots I take of the shift do not show it in the screenshot. An LG tech advisor told me that if the screenshots are good, the video signal to the monitor is good and that it's likely a monitor issue. I don't believe that is true in this case though.

K9x3 Author

Level 1

21 points

Dec 29, 2020 1:55 PM in response to defender90rover

I read somewhere that a forthcoming update is supposed to address issues with the ultra wide monitors. I agree, to many people with the exact same suggests an issue with the Mini. Thanks for posting your experience.

Dec 31, 2020 7:39 PM in response to K9x3

Hi K9x3, I have been using my monitor for a year now (though at 4k resolution before getting Mac mini recently), and it never had that vertical band issue. Its only after moving to M1 Mac mini that I get the vertical band, and it made me think its a software issue with Mac mini. Where did you find the contact details for LG technician, and how did you go about communicating with Apple to get this resolved? Thanks! Here's the link to the issue that I filed: https://discussions.apple.com/thread/252228225?login=true

K9x3 Author

Level 1

21 points

Jan 13, 2021 7:52 AM in response to digitalsr2

Thank you for the response. Based on your experience, the M1 architecture is not a common thread if your intel 16" MacBook Pro is having the exact same same issue (approximately a two inch vertical band shifted several pixels up, with the right edge of band aligned with camera).

Did you run the monitor from your intel Mac Pro laptop with Catalina, and if so, did this issue begin after the Big Sur update?

FYI, I setup a hot corner (like someone else had recommended) to put the system to sleep and then wake it. Usually on the first or second attempt, the issue is temporarily corrected.

K9x3 Author

Level 1

21 points

Jan 13, 2021 1:24 PM in response to digitalsr2

Interesting -- so the common threads are the monitor, the thunderbolt 3 interface, and the MAC operating systems since Catalina.

It would be interesting to know if any 5K iMacs have had this issue, since the display panels are reportedly the same.

Jan 14, 2021 8:24 AM in response to K9x3

I have a M1 MacBook Pro 13 and use a LG 27" 5K (27MD5KL) as a secondary display to the internal MacBook display. I also experience the in this thread named "vertical pixel shift" (located off centered; slightly to the left). For me, putting the mac to sleep and waking it up again "fixes" it, which is usable since these new machines wake up that quickly with TouchID.

Another issue I have is, that the resolution of the internal retina display sometimes changes, when I put the mac in sleep and wake it up again (whole time connected to the LG display). In this case only a reboot solves the problem for me.

Jan 14, 2021 12:10 PM in response to K9x3

I am having the same issue with the vertical pixel shifting and thought it might be beneficial to add that it is occurring while running windows with bootcamp. the width of the band of pixels sometimes skinner and sometimes wider. Its driving me crazy trying to troubleshoot.

16" MacBook Pro late 2019

5k LG

Has anyone tried a different thunderbolt cable. is it possible the LG one is defective?

Jan 14, 2021 12:24 PM in response to K9x3

I think its also worth noting that the vertical band of pixel shift occurring is actually in the very middle of the screen since the camera is offset slightly. A lot of people have been stating that the vertical band is slightly left of center.

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M1 Mini issue with LG 27" 5K Monitor