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davidcmc

macrumors 6502
Original poster
Nov 5, 2009
318
55
Until El Capitan, OS X/macOS doesn't have a friendly UI to disable the built-in display while an external one is attached. All you can do is fully decrease the built-in display brightness, but even though there's apparently nothing being displayed, if you look very closely you'll notice that the system is still rendering image on the built-in display.

Yea, I can use in clamshell mode, but I'd rather not let the heat created by the chassi internals hit the display. I know Apple recommends using this clamshell mode, but I still think the user should be free to disable the built-in display whenever he wants.

The brightness trick isn't very good because it still makes the GPU use it's processing power to render useless image on a display. It indeed consumes processing power, as you can read this testimony: https://discussions.apple.com/message/30390201#message30390201.
 

leman

macrumors Core
Oct 14, 2008
19,497
19,632
If you need this feature, submit a bug report to Apple with a feature request. But I would't be very optimistic here — Apple is not known for implementing niche functionality like this.

P.S. There is of course Ctrl+Shift+Power, but I have no idea what it does for multi-monitor setup
 

davidcmc

macrumors 6502
Original poster
Nov 5, 2009
318
55
If you need this feature, submit a bug report to Apple with a feature request. But I would't be very optimistic here — Apple is not known for implementing niche functionality like this.

P.S. There is of course Ctrl+Shift+Power, but I have no idea what it does for multi-monitor setup

I remember Leopard and Snow Leopard with this feature. They've removed it for some unknown reason (maybe to force people to use the Retina displays?).

The Ctrl + Shift + Power shortcut actually puts ALL displays (including the external one) to sleep. It's useless for what I want to do here.

Thank you.
 

PhiLLoW

macrumors 6502
May 31, 2014
325
184
Theres an App for that :O

I really hate the way macOS handles multiple monitors but I've got "DisableMonitor.app" and "SwitchResX" which make display settings much better.

Unfortunately you'll still need a third party solution on Sierra
 

tom753

macrumors newbie
Sep 11, 2016
1
2
I use a small permanent magnet to disable the build-in display. The MacBook will get the signal that the lid is closed. As keyboard and trackpad remain active that's a perfect workaround for me.

You will have to find the right spot to put the magnet for your MacBook. For a MacBookPro late 2008 it's on the right side just below the speaker...
IMG_6800.JPG
 
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tywebb13

macrumors 68040
Apr 21, 2012
3,078
1,745
I use a small permanent magnet to disable the build-in display. The MacBook will get the signal that the lid is closed. As keyboard and trackpad remain active that's a perfect workaround for me.

You will have to find the right spot to put the magnet for your MacBook. For a MacBookPro late 2008 it's on the right side just below the speaker...
View attachment 650165

That's cool. Where can one buy such magnets?
 
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