Using only the external display on a MacBook

I've been looking for a way to use the external display only on my MacBook for a long while. There are a few workarounds online but, to me, all have dealbreaking disadvantages.

First, there's the "as it was supposed to be" clamshell mode. This means you have to hook up the display, close the lid and things will magically work. Well, it's not that easy. It turns out you have to have your laptop charger plugged in. And no, you can't get clever on it - if you unplug the charger while the lid is closed and you are hacking away on your external display, the laptop will go to sleep. Besides, keeping the lid closed has a significant impact on heat dissipation. Overall, no go.

OK, so we want to have the lid open. Well, there's a hack online that suggests using some boot args / nvram magic that disables the display entirely. This means you have to reboot when you need this functionality. Then, if you want to restore things, you need to change the args back and reboot again. Oh, and if you forget to do this and the display is not attached - no worries, you can simply reset your laptop's PRAM. Hmm.. I think I'll pass.

Setting my frustrations with the current solutions aside, here's a hack that I have discovered to work:

  • download and run the awesome DisableMonitor app. (@Eun, thanks a lot for writing this!)
  • plug in your external display
    • you should now have an extended desktop setup
  • go to the system status bar, and using the DisableMonitor icon, set the resolution of the laptop screen to the resolution of the external display
  • go to System Preferences > Displays and enable display mirroring
    • you should now see the same stuff on both displays, with things looking most probably funky on the laptop display - that's fine, you won't need it
  • turn down the laptop display brightness all the way (i.e. shut it off)

Good, we got to where we wanted - using the external display only. But the win is here: if you unplug the external display, the laptop display will come back on with the proper resolution set. And if you plug the external display back in, the settings you made earlier will be restored (you only have to turn down the brightness on the laptop).

I know it's not perfect, but this is as close as I managed to get towards the holy grail of running my MacBook on the external display only. Let me know if you know a better way!

Mihnea Dobrescu-Balaur

Building @Hootsuite Analytics. Interested in Open Source, programming languages and the Open Web. Big fan of basketball and photography. Tweet @mihneadb.

Bucharest, Romania

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