Apple Intelligence is now available on iPhone, iPad, and Mac!

⏺ Press release

⏺ Learn more

⏺ Watch the video

📢 Newsroom Update

Apple unveils the new iMac with M4, supercharged by Apple Intelligence and available in fresh colors. Learn more >

📢 Newsroom Update

Apple’s all-new Mac mini is more mighty, more mini, and built for Apple Intelligence. Learn more >

Looks like no one’s replied in a while. To start the conversation again, simply ask a new question.

M1 Macbook Pro - Dell External flicks from on to black, back and forth

Have seen other people out there with the same issue - I have 2 M1 Macbook Pro's at my house and they both do the same thing. Plug in my 2 new Dell S2721QS 4k monitors and immediately one of them will start flashing black and then come back, then black again and so on.

I am connecting these monitors using DP to USB-c cables into the USB-c ports on the machines directly.

I have tried swapping cables, no difference.

I also have a 2019 Intel Macbook Pro and the screens work perfectly for this machine everytime.

In order to resolve this issue, I keep having to adjust the display settings until the screen stops flashing, but this only works for a limited time, the next time I connect the screens or turn the computer on we are back to square one. I can also remove the cable and plug it back in a number of times, and eventually the screen stays on.

MacBook Pro (2020 and later)

Posted on Feb 16, 2022 1:41 PM

Top-ranking reply

Why Can't I sign in Author

Level 1

8 points

Posted on Feb 18, 2022 3:55 PM

I had previously bought another DP to USB-c cable and had the same issue.

I have now realised that one of the monitors/cables seems to work everytime - so I swapped that cable to the other monitor and now that one works everytime. So even though I have tried 2 different DP=>USB-c cables on one monitor and had the same results, it seems both of those cables might have been not high quality enough.

I also tried a high quality HDMI cable and it is working.

Finally I tried the good DP => USB-c cable with a USB-c cable extender, and it stopped working. So it would seem that the quality of the cables is really important here, I am not sure of the specs, but if you come across this issue that might be your problem.

View in context

M1 Macbook Pro - Dell External flicks from on to black, back and forth

Similar questions