I'm having this problem where my computer performs some weird behavior when I turn off my external monitor. For example, I have to run some programs and I'd like to have my screen off because they take many hours to run. However, when I turn off my monitor it seems to stop the program. How can I make my computer not notice when I turn off my screen? I have a Dell monitor and a Mac Mini with macOS Sierra.
I suspect the best way to manage your situation is via some of your System Preference settings.
More specifically, try the following and let me know how you go:
- Go to System Preferences
- Select Energy Saver
- Set your Computer Sleep to Never
- Set your Display Sleep to a short period
- Ensure that Put hard disks to sleep when possible is unchecked
- Now exit Energy Saver and select Desktop & Screen Saver instead
- Select the Screen Saver tab
- Ensure that the Start after setting at bottom left is set to Never
- Exit System Preferences
Now try using your Mac Mini as you want, but don't turn off your monitor until after it has gone to sleep. Let me know how you go.
As an aside, is there a reason you want to physically turn your monitor off?
Your monitor uses less than 0.3W when it's in sleep mode, so you're not really saving much in terms of energy by shutting it off instead of letting it sleep. So, if you set your Energy Saver settings as above, the amount of energy consumption while your monitor sleeps is negligible and your Mac Mini can still perform what it has to.
For future reference, if you connect your monitor through DVI (I use a Thunderbolt-to-DVI adapter) it seems the Mac won't be able to tell if the monitor is on or off.
I don't know if that's specific to my Thunderbolt-to-DVI case, but I would guess it's on the DVI end.