Sometimes I see slant black lines running diagonally on the screen, about 1 centimeters of the display's top portion when opening certain windows. like today, I saw them in Chrome in AI Mode. Restarting fixed the issue, but, this has happened in the past.
How can I know whats wrong? I think its my mac mini and not the dispay as only certain windows show this issue and rebooting fixed the issue.
Neerav
Mac mini, macOS 26.1
The latest macOS versions have made video output from the HDMI port more temperamental.
(plus older thin long HDMI cables and their connectors can be damaged by heat)
The only way to troubleshoot the problem at home, is to test a different HDMI cable.
(preferable a short high speed HDMI cable like the ones I suggested above)
Another option if you have a problem with the Mac mini's HDMI port.
(is to get and use a USB-C to HDMI cable)
If that is an older thin 2m/6' Apple or Belkin HD HDMI cable..?
Test a short 1m/3.3' certified high speed HDMI 2.1 48Gbps cable.
for a couple of examples from Amazon:
Do you have a 2020 M1, 2023 M2 or 2024 M4 model Mac mini...?
see > Identify your Mac mini model - Apple Support
What make/model is the display and what type of cable are you using..?
Its an apple cable one with a titanium connector. I have another of this connected to my set top box as well. That one is even a little worn out but has no problem.
So i dont think its the cable. I think its the mac. How can i test at home.
Mac mini m1. Lg full hd display. Apple hdmi cable.
Mac mini: Diagonal black lines at top of screen in some apps
