Display pixels duplicated on Mac mini M1

Setup:

Mac mini (2020) Apple M1 - 16g Ram, 500GB Flash Storage


Display:

2008 Apple LED Cinema Display 24-inch (1920 x 1200) - single in use


Issue:

An area of pixels are being duplicated on display. Using the coordinates from the screen capture tool (Cmd + Shift + 4), the source area of duplication is from x352, y1999 ~ x388, y1999 (very bottom, near left side) and are being displayed/duplicated at x959, y0 ~ x996, y0 with pixels x997, y0 & x998, y0 flickering (very top of the display just beneath and to the right of the iSight camera).


Method of Connection:

Two 3rd-party USB-C/Thunderbolt 3 to Mini Display port adapters. One from Answin and another from UPTab (w/ Power Port) specific for Apple M1 Mini, MacBook Pro/Air.


Steps Taken to Diagnose Issue:

The issue is the exact same (same location, effected pixels) with either 3rd-party adapter, and while connected to either of the two USB-C/Thunderbolt 3 ports in the rear of the 2020 Mac mini M1. Both 3rd-party adapters are free of defects and have been tested by connecting the same Apple LED Cinema Display to a 2018 MacBook Pro w/ USB-C/Thunderbolt 3 without issue on display. The display also shows zero issues when connected directly to an older Mac mini (2012) via the Mini Display Port.


  • Display connected via MiniDisplay Port to Mac mini (2012) :: No issue
  • Display connected via Answin adapter to MacBook Pro (2018) :: No issue
  • Display connected via UPTab adapter to MacBook Pro (2018) :: No issue
  • Display connected via Answin adapter to Mac mini (M1 2020) USB-C port-1 :: Specified Issue
  • Display connected via Answin adapter to Mac mini (M1 2020) USB-C port-2 :: Specified Issue
  • Display connected via UPTab adapter to Mac mini (M1 2020) USB-C port-1 :: Specified Issue
  • Display connected via UPTab adapter to Mac mini (M1 2020) USB-C port-2 :: Specified Issue


Specified Issue :: Meaning the exact location on the screen with zero deviation

Changing screen resolution from System Preferences yielded no difference in outcome. Same location on screen.


Below are some photos taken of the issue discussed. Will I need to send the unit back - it was shipped from China due to the configuration (16gb RAM & 500 GB SSD)? What route is there to resolve the issue?


Note both the top-right above the "discussions.apple.com" url in the browser where the mouse icon is being duplicated & bottom-left where the mouse icon is below the Mail app icon in the dock.


Close-up photo of the Botton-left of display:


Close-up photo of the Top-middle of display (note the black w/ white outline of the mouse icon):

Mac mini, macOS 11.1

Posted on Jan 19, 2021 5:23 PM

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Posted on Jan 27, 2021 10:04 AM

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13 replies

Jan 21, 2021 2:48 PM in response to Eric Shinn

Hi there, Eric,


Welcome to the Apple Support Communities!


We understand that you're seeing some issues with your display connected to your Mac. You've done a great job troubleshooting so far. Thanks for including those details.


Check out the additional steps outlined here to help address this behavior further: Get help with video issues on external displays connected to your Mac


We hope this helps.


Cheers!

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Display pixels duplicated on Mac mini M1

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