Brand New M1 Mac Mini - weird artifacting on second screen

[sdwaltz]

Picked up an M1 Mac mini on Monday - to say I'm impressed with the capabilities is an understatement. This thing is seriously impressive, especially for $700.

I run two monitors at my office, nothing special, just plain old 1080p on each. For awhile after startup, and sometimes after waking up from sleep, I get some small, weird artifacting that occurs on the "inactive" screen.

Behaviors:
1) only happens on inactive screen.
2) It only seems to happen when it's on the desktop itself with the Big Sur wallpaper. If I drag a window on top of it, it goes away.
3) Stops after the computer has been running for a few minutes

I am using USB-C to HDMI for my primary screen, and the HDMI port for my second screen. I have changed HDMI cables to see if it was the cable itself...no cigar.

EDIT: Additionally, the "main" screen will go black for random amounts of time without warning.

Anyone else have anything like this going on?

 

[robbieduncan]

Have you tried swapping screens over? Just to rule out the possibility it’s related to the screen itself. I would have bet on a cable problem but you’ve already tried that

 

[sdwaltz]

Have you tried swapping screens over? Just to rule out the possibility it’s related to the screen itself. I would have bet on a cable problem but you’ve already tried that

I haven't, but I don't need to - I know the monitor is fine because I also have a Windows PC hooked up to it (I have a couple use cases that require Windows) and the 2012 Mac Pro that this Mac mini replaced did not have the issue.

 

[airbatross]

I just bought my M1 mini yesterday and yes it happened to me a couple of times. I changed wallpapers but it was still there. It was like line of weird coloured long dots.. Restart made it go away.

Come to think of it, it never happened after I formatted and reinstalled big sur (I had problems with installing apps after upgrading to 11.0.1 from 11.0 out of box so wanted to erase the drive and reinstall.. I also had reinstall drama like everyone had)

If it happens again I’ll take a screenshot. I have Dell P2419HC btw connected to mini via USBC