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 18, 2021 5:49 PM in response to Chris Wilhoite

Its odd you would have 1st gen after only purchasing a month ago. I thought the switch to 2nd gen was quite a while ago. I would try to exchange for a gen 2.

Apr 16, 2021 9:27 PM in response to K9x3

Same issue persists on Big Sur.

I thought it was a cable connection problem so I went and got the Thunderbolt 3 Pro cable from apple but that didn't help either. I hope the next update helps.

MEADEN

Level 1

15 points

Dec 11, 2020 10:44 PM in response to K9x3

Not having this issue. I have Apple Mac mini M1 (16Gb) and LG 5K (27MD5KL).

My issue is when it returns from sleep, there is an inch / inch-and-a-half wide section vertically down the middle that is offset by a few pixels.

K9x3 Author

Level 1

21 points

Dec 12, 2020 5:54 AM in response to MEADEN

I had this exact same problem and attributed it to a monitor defect after talking with an LG technician. The LG tech said to take a screen snapshot of the defect. If the defect is not in the screenshot, then the defect is with the monitor. If the defect is in the screenshot, then it is in the signal from the computer. In my case, the vertical section was shifted up by a few pixels the full height of the monitor, with the right edge of this vertical section just left of center on the monitor. When experiencing this issue, I could drag any window, image or even the screenshot across this section of the monitor, and the pixels would shift moving across that section.

In my case, the defect was not in the screenshot, so I attributed it to the monitor as LG suggested and got authorization from apple to return the monitor. I've purchased the replacement monitor and have not seen the issue this far.

I was hoping this defect was the root of my other problem with the resolution changing to 4K, but it is not, and I'm getting a replacement M1 mini next week from apple.

Thanks for the reply, this gives me hope.

Dec 12, 2020 8:21 AM in response to K9x3

I'm having a very similar problem. On sleep or reboot, my LG 5K falls back to 4096x2304, and I have to unplug the monitor power cable to get my new M1 Mac Mini to recognize it as 5120x2880. Ah, the joys of first-gen hardware!

Jan 13, 2021 9:07 AM in response to digitalsr2

I tried to post this from my iPad but it failed twice. I have both a MBP 16” and a MBA. The MBP 16” had trouble waking up with the first generation of 5K LG display so I swapped to the second and didn’t have *any* trouble after that. The M1 MBA has this problem.

Jan 14, 2021 8:59 AM in response to K9x3

Thank you for your quick response! :)

Yup, I'm running 11.1. I don't experience any resolution problems on the LG display, it always displays the 5K resolution.

The "internal display problem" only occurs while being connected to the 5K display. While just working with the internal display and even while being connected to an old Dell 1080P Display (via Apple USB-C AV Adapter (HDMI)) this problem never happened to me. I got to say though, that I watched some YouTube videos after the M1 launch of early M1 buyers who also had problems with third-party (I mean not "made for mac"-branded) 4K displays. I think (unfortunately not sure anymore) someone had the resolution shift on the internal display also with a not LG-"made for mac" display.

I have the feeling somethings are still off on these new macs regarding "displaying stuff". (Let's hope only software-wise)

K9x3 Author

Level 1

21 points

Jan 16, 2021 12:47 PM in response to Chris Wilhoite

Chris,

I did not use the cable labeled USB-C MacBook iPad Pro. I used the cable marked Thunderbolt 3 (usb-c) for multiple devices, including the Mac mini.

I've used the following cables, and all have had the same issue with the pixel shift.

two differnt Thunderbolt 3 (USB-C) cables that came with the two different LG 5K monitors from the Apple Store (one monitor was returned, believing the monitor was at fault)
The Thunderbolt 3 cable (.8m) from the Apple Store - $39
The Thunderbolt 3 Pro cable (2m) from the Apple Store - $129
The Thunderbolt 3 cable that shipped with the CalDigit TS3 Plus Thunderbolt 3 Dock

In all cases, I connect the monitor to the mini directly by TB3. I connect my Caldigit TS3 Plus dock to the mini directly as well, using the second TB3 port on the mini. I then connect all my peripherals to the CalDigit TB3 dock. I currently do not use the USB-C connections on the back of the monitor.

I hope this helps

Jan 16, 2021 5:27 PM in response to K9x3

Yes, I'm running Catalina 10.15.7 on late 2019 16" MacBook Pro and encountering the pixel shifting at center. Recently I decided to use the LG included USB-C instead of the thunderbolt. I haven't had an occurrence in a couple days since switching (fingers crossed). Has anyone else encountered the problem with using USB-C instead? Maybe its a problem with the thunderbolt cable spec?

K9x3 Author

Level 1

21 points

Jan 16, 2021 5:39 PM in response to Ross Ellingson

Ross, I agree on it potentially being in the Thunderbolt 3 spec. You've effectively eliminated the M1 architecture and Big Sur as common threads in the issue. I don't know what the spec differences are in the two different cables sent with the monitor. When you use the USB-C cable, are you using one of the three usb-c ports on the back of the monitor vice the single TB3 port?

I'm also curious if anyone with the 5K iMacs experience this issue with the built-in monitor. If not, this could also indicate an interface issue (presuming the 5K panels are the same and a different interface is used for the display panel in the iMac.

Thanks for the additional info

Jan 18, 2021 4:02 PM in response to K9x3

Hi Jon,

My monitor is doing 5k just fine as far as I can tell. When I was using thunderbolt 3 and chose other resolutions the problem of the shifted pixels remained. No matter what I selected. So far I don't see any limitation by using USB-C over thunderbolt.

MEADEN

Level 1

15 points

Jan 18, 2021 5:10 PM in response to K9x3

I couldn't get the LG Screen Manager to do anything useful on the M1 - so I fired it up on an Intel MBP and connected the screen to that, and the app then successfully detected the monitor - but told me the firmware was up to date. Screen shot of the version numbers attached FYI.

K9x3 Author

Level 1

21 points

Feb 4, 2021 1:29 PM in response to dre1138

Thanks Doug. I too have had the issue reoccur with the replacement M1 mini and OS 11.2. One thing I noticed after my clean install was that I had only one LG UltraFine Display profile (System Preferences - Displays - Color Tab) after the clean install and now I have two. I've always noticed two in my prior configuration, and I wonder if the second showing up has any role or effect in the issue.

I've exhausted all my opportunities to potentially resolve the issue and have to hope Apple resolves it or switch to a 4K monitor and see what that yields. .

Thanks for the feedback

Thanks for the response.

Feb 8, 2021 11:54 AM in response to K9x3

I am having this exact issues on an M1 MBA. I have swapped out a variety of new cables and nothing makes it stop reoccurring.

I am running 11.2.

the Sleep hot corner has shown some success, but it eventually comes back.

earns

Level 1

4 points

Mar 13, 2021 1:56 AM in response to Chris Wilhoite

I also have the vertical shift problem. After setting the energy saver to never, as Chris Wilhoite suggested, since two days this problem has not occurred again. May be here we have the faulty process? I will reply again, if the shift shows up again despite the new energy saver setting.

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M1 Mini issue with LG 27" 5K Monitor