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macrumors newbie
Original poster
Oct 26, 2021
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tl;dr: I had this issue with an M1 Mac mini which I returned back in July. I'm not sure how I triggered the issue but from what I remember it maybe had to do with black/dark backgrounds. Let me know what triggers it for you and I can test it with the new M1 Pro (16-inch) MBP and I'll keep you updated. It's also in my best interest to do this testing as extensively as possible because the return window is only 14-day.

I bought an M1 Mac mini back in July and was pleased with the performance but I encountered this "flickering" issue with external displays and unfortunately had to return it. I initially thought it was my display (Dell U2718Q) that was broken and asked Dell to exchange it under warranty. Dell didn't have the U2718Q so they sent me a (refurbished) U2720Q which is basically the 2020/improved version of the U2718Q (which was released in 2018). I continued to have the same issue and suspected there was something wrong with the Mac mini rather than my monitors. During this whole time (before, during, after) I had/have been using my Windows computer with the both monitors without issues (running at the same 4K resolution and 60Hz refresh rate). So it's definitely something wrong with the M1.

I will receive my 16-inch M1 Pro 16GB memory 1TB storage today and will be testing it with my U2720Q (as well as another monitor I have which is the Dell P2421). You can look up the specs of these monitors if you're not familiar but basically the U2720Q is a 4K (2160p) panel and the P2421 is a 1080p. To avoid falling to perform an extensive test of this issue, let me know the ways in which the issue gets triggered for you and I can test those in addition to browsing Reddit.com in dark mode (which was one of the things that triggered it for me from what I remember -- it's been a while)
 
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tl;dr: I had this issue with an M1 Mac mini which I returned back in July. I'm not sure how I triggered the issue but from what I remember it maybe had to do with black/dark backgrounds. Let me know what triggers it for you and I can test it with the new M1 Pro (16-inch) MBP and I'll keep you updated. It's also in my best interest to do this testing as extensively as possible because the return window is only 14-day.

I bought an M1 Mac mini back in July and was pleased with the performance but I encountered this "flickering" issue with external displays and unfortunately had to return it. I initially thought it was my display (Dell U2718Q) that was broken and asked Dell to exchange it under warranty. Dell didn't have the U2718Q so they sent me a (refurbished) U2720Q which is basically the 2020/improved version of the U2718Q (which was released in 2018). I continued to have the same issue and suspected there was something wrong with the Mac mini rather than my monitors. During this whole time (before, during, after) I had/have been using my Windows computer with the both monitors without issues (running at the same 4K resolution and 60Hz refresh rate). So it's definitely something wrong with the M1.

I will receive my 16-inch M1 Pro 16GB memory 1TB storage today and will be testing it with my U2720Q (as well as another monitor I have which is the Dell P2421). You can look up the specs of these monitors if you're not familiar but basically the U2720Q is a 4K (2160p) panel and the P2421 is a 1080p. To avoid falling to perform an extensive test of this issue, let me know the ways in which the issue gets triggered for you and I can test those in addition to browsing Reddit.com in dark mode (which was one of the things that triggered it for me from what I remember -- it's been a while)
Can you try booting in to recovery mode and playing around with the ui elements there? That triggered it for me.
  • Press and hold the power button on your Mac until you see “Loading startup options.”
 
1) Must be in Dark Mode.
2) It seems to happen randomly, but Youtube really seems to send it into a tizzy.
3) It still happens on my M1 Pro MBP 16", but nothing like it did with my M1 Mini.
 
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