M1 Mac Mini vertical lines/bands on external displays

[CaffeinePizza]

I have two Asus VS248H monitors (one of them is only a year old and the other is 7-8 years old). I know they aren't new models. The most modern port they have is HDMI. Anyway.

I've seen this issue only a couple of times on the Internet, but I don't know what keywords to use in my search, so I'm calling it "vertical lines."

A pattern of vertical dark lines of equally spaced distance goes across both monitors. I don't have another set of monitors to test besides my TV, which didn't show the issue, but TVs also do a bit of image processing so it isn't conclusive.

This doesn't seem visible on all colors, but shades of gray is where it is most visible.

The issue is not present on these monitors when using my desktop PC or connecting my 2017 MacBook Air to them. I've tried different HDMI cables. Nothing super high end like 8K cables, because I don't own devices that need them. I am using the HDMI port on the mini and an Anker USB-C to HDMI port for the second screen.

I'm beginning to believe it's an issue with the M1 graphics processor to be honest. I'm within my return period for this Mac mini. But I like the computer and would hate to return it.

I've attached an image to show the pattern I'm talking about. It's very hard to get my phone camera to show the pattern and not a moire effect.

thanks for your suggestions and help.

 

[CaffeinePizza]

Got another monitor of mine I was letting someone borrow (albeit only DVI not HDMI). Passive HDMI to DVI adapter. Same HDMI cable. Same pattern. Adjusting contrast makes it go away and come back, totally dependent on the shade of gray the screen is. I don't understand.

 

[CaffeinePizza]

Ordered belkin cables from Apple. No difference. shrug

 

[CaffeinePizza]

Well. The AppleCare has been refunded and the return label printed. Upsetting that it has to be this way. I'm not buying brand new monitors to accommodate a computer when every other computer I've plugged into them worked 100% fine.

 

[wilberforce]

Sorry to hear you found no solution. I read your post and was going to suggest a few things, but realized I was just guessing which would not be productive. It seems like there is some aliasing going on, like due to a mismatched resolution, but I don't know.

 

[CaffeinePizza]

Sorry to hear you found no solution. I read your post and was going to suggest a few things, but realized I was just guessing which would not be productive. It seems like there is some aliasing going on, like due to a mismatched resolution, but I don't know.

The resolution appeared normal at 1920x1080. I think it's a hardware issue with M1 graphics. It doesn't seem to affect everyone. I'm not sure why. Hopefully Apple will fix it. I would like to have a new Mac

 

[caru]

Just bought a MacBook pro 14'', I have exactly the same issue on my external monitor Eizo CS230 connected through HDMI (1920 x1080 @60Hz).

The banding is mainly vertical and is well visible mostly on dark mid-gray colors.
Very annoying on such an expensive device.

I am concerned it might really be an issue with the GPU, there are too many reports online about the M1 (can be a Mac mini, macbook pro M1, macbook air M1 etc etc).

Has anyone found a solution?

 

[opeter]

I would like to help, but sadly, I think this is either a software or hardware problem. The software part could be eventually fixed by Apple, if they know how to do it or what to do. Or they will simply put out a statement (wouldn't be first time), that the M1 Mac is compatible only with devices A and not B.

Some of us are waiting for the 2nd generation of Apple Silicon SOCs with the hope, that there won't be many (such or similar) problems.

 

[caru]

I whish I had found this (and many more) threads before buying, but even in this case it may not have helped as it is always very hard to figure out how widespread an issue is from online reports.

 

[opeter]

The interesting thing is, that some problems didn't show up in macOS 11 Big Sur, but rather with the next iteration of macOS 12 Monterey. But since you computer cannot run Big Sur, it is not posibble to make a test in this matter.

Than there are always new bugs introduced like this one two months ago (this should be fixed now, I think):

Users Report External Monitor Issues After Updating to macOS Monterey 12.3​

Users Report External Monitor Issues After Updating to macOS Monterey 12.3

Following the latest macOS Monterey 12.3 update, users are reporting several problems when using external monitors, ranging from Macs not detecting...

www.macrumors.com

 

[MajorFubar]

Seems the video chips in these M1 machines are very choosy over their monitors. My Studio Max wouldn't so much as show a picture on my Samsung U28R550UQR when connected HDMI->HDMI. The only other input in the monitor is Display Port. I had to borrow* a HP G5 USB C docking station from work which mercifully has a Display Port output. Previously I'd used the HDMI input on that monitor to display video from a 2010 Mac Mini, a 2013 MBP, a recent Windows laptop and even a Panasonic BluRay player, all with zero issues. M1 Mac? No way, José.

Betcha Mac Minis just so happen to work great with the Mac Studio display...

 

[CaffeinePizza]

The interesting thing is, that some problems didn't show up in macOS 11 Big Sur, but rather with the next iteration of macOS 12 Monterey. But since you computer cannot run Big Sur, it is not posibble to make a test in this matter.

Than there are always new bugs introduced like this one two months ago (this should be fixed now, I think):

Users Report External Monitor Issues After Updating to macOS Monterey 12.3​

Users Report External Monitor Issues After Updating to macOS Monterey 12.3

Following the latest macOS Monterey 12.3 update, users are reporting several problems when using external monitors, ranging from Macs not detecting...

www.macrumors.com

I was sure the vertical banding issue existed in Big Sur, but maybe I'm wrong?