I have a 2018 Mac Mini running macOS Monterey 12.6.

The Mac is connected to a single external monitor using HDMI.

Whenever the Mac wakes from sleep or is restarted normally, the monitor has no signal. I am still able to ssh into the machine when this happens, but there are no displays listed. Using a different external monitor from a different brand, using a different HDMI cable, or switching to a USB-C connection does not fix the problem.

The only thing that consistently fixes the problem is restarting the computer and holding down the keys Cmd+Opt+P+R to reset NVRAM. However, this only works for one restart, and the monitor will say no signal again the next sleep/restart.

I look at the NVRAM variables after the reset and the only variable that seems potentially relevant is HW_BOOT_DATA but it is not clear to me how to interpret that data.

I would like to find a solution to this problem that does not involve resetting NVRAM and restarting.

  • Have you tried another HDMI cable?
    – IconDaemon
    Commented Sep 20, 2022 at 19:36
  • @IconDaemon Yes, updated the question.
    – mushroom
    Commented Sep 21, 2022 at 2:46
  • Have you tried making a test user account and seeing if the monitor acts the same way?
    – agarza
    Commented Sep 21, 2022 at 3:49


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