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I own a Macbook Pro 13 2017 (2 thunderbolt ports), and I would like to disable the internal display when an external monitor is connected to it through USB-C.

I have ruled out the following

  1. Turn brightness all the way down in mirrored display mode: Not the best, because the GPU's framebuffer is still doing extra work on that internal display (processing power and battery affected).
  2. Using Clamshell mode: Again, not the best. I only got two USB-C ports, one would be taken by AC power which is a prerequisite for this mode, and another displaying to the external monitor.
  3. Add "niog=1" on NVRAM: Sounds OK, but still a hassle to reset NVRAM every time I want to work on the internal display.

I can think of two solutions

  1. Simulate what is happening to macOS on Clamshell mode without actually closing the lid.
  2. Simulate the Macbook on AC adapter power so I can use Clamshell mode with one USB-C port free.

I would appreciate feedback on this, it would be great to nail this issue.

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  • 2 sounds the best solution. Can you use pmset so you can close the lid? This works for me but my MBP is older. See answer to this question for details : apple.stackexchange.com/questions/296293/…
    – lx07
    Commented Mar 13, 2019 at 15:55
  • It seems that setting the lidwake to 0 has no effect anymore, it is mentioned on many rants/forums.
    – Denicio
    Commented Mar 13, 2019 at 16:46

1 Answer 1

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Why not put a small and not super powerful magnet on the specific area of the sleep wake sensor so that the system thinks the lid is shut?

With power and keyboard connected, you'll have it running in closed-clamshell mode with full benefits for your use case and no need to move the actual display.

There are amazing USB-C pass through docks now - some that sit flush and others with a stand off cable so you can get around the limitation of only having two ports if that's the only sticking point for clamshell mode.

The good adapters are still in the $50 US range, but the knock off ones are rapidly approaching $10 so you can pick metal or plastic and your warranty / support model of choice if you run out of ports.

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  • Thanks for answering. I would not mind the idea of a small magnet as you mentioned, but my problem with this solution is the inability to cast 4k @ 60hz using these external Multiport hubs. Could you also share a photo as to where would that magnet go on a Macbook Pro 13" 2017?
    – Denicio
    Commented Mar 10, 2019 at 20:13
  • I don’t have that Mac to test now, but you can look it up in iFixit or just move one until you find wher e it triggers your Mac. As long as it’s not a super magnet, you won’t hurt anything triggering it. Do you run one or two 4K @Denicio - I use a 4K cable for that alone and put the charge / other things on the hub.
    – bmike ♦
    Commented Mar 10, 2019 at 20:30
  • Just one 4K TV synced at 60hz connected through Satechi USB-C 3.1 to HDMI 2.0, so I don't want to lose that capability.
    – Denicio
    Commented Mar 10, 2019 at 20:43
  • Dang - that’s one of the good adapters in my experience. Hopefully someone has a better answer short of an EGPU that runs off Thunderbolt 3 or a TB dock.
    – bmike ♦
    Commented Mar 10, 2019 at 20:44
  • I know, at first I had a Samsund Dex cable with a USB-C 3.0 interface, and it would randomly switch between 30hz and 60hz each time I plugged it in, so frustrating. Thanks for all the help @bmike!
    – Denicio
    Commented Mar 10, 2019 at 20:48

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