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How do you turn off the MacBook Pro’s display with the lid open while using an external monitor on Mac OS X 10.10 Yosemite?

All the previous methods—such as the one’s listed here—that have worked on Mavericks no longer work on Yosemite.

Does anyone know the way to do this on Mac OS X 10.10 Yosemite? Turning down the brightness is not the same as turning off the display as the GPU still sends a signal to the internal display and the external monitor.

These were the terminal commands to achieve this on Mavericks:

Enable

sudo nvram boot-args="iog=0x0"

Disable

sudo nvram -d boot-args

Anyone know how to achieve this on Yosemite?

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    Yeah, sadly this appears to be something that regressed with the release of Yosemite. One would think this to be a feature by now. Ugh. – TechTrip Oct 29 '14 at 23:32
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    I share you sentiments exactly, you would think such a basic feature would be included. Still holding out hope that someone will find a software workaround to this soon. – chance Oct 30 '14 at 2:47
  • Hi, agree experimenting with this I can get it to work only by closing the lid. As long as the laptop is plugged in it doesn't sleep. Thus you need a usb keyboard and mouse to quirk with this setup. A concession until Apple fully addresses the issue. – TechTrip Oct 30 '14 at 15:59
  • Right, well that's intended behavior by closing the lid, using a usb kb and mouse. I prefer to keep the lid open for additional airflow as the heat that rises from the keyboard doesn't get trapped from underneath the closed clamshell. – chance Oct 30 '14 at 20:11
  • possible duplicate of How do I turn off laptop display when I have an external display? – Basil Bourque Aug 1 '15 at 23:59
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The equivalent command for Yosemite is:

sudo nvram boot-args=niog=1

I've only tested it on my Late 2008 15-inch MacBook Pro, but it works for me. Your mileage may vary.

Source: I read the IOGraphics source code, specifically IOGraphicsFamilyModuleStart() in IOFramebuffer.cpp.

Technical details: We need to clear bit 0 (kIOGDbgLidOpen) in the module's gIOGDebugFlags variable in order to change how it handles lid open events.

Previous versions of the code would set this variable to whatever value iog specified in the boot arguments, or 0x03 if iog wasn't specified.

The code in Yosemite first sets gIOGDebugFlags to 0x43, then bitwise ORs it with the value specified by iog (if it exists), and finally bitwise ANDs it with the bitwise complement of the value specified by niog (if it exists). In other words, iog can now only set bits in gIOGDebugFlags, but the new niog can clear bits. So we specify niog=1 in the boot arguments to clear bit 0.

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  • How do we remove this command if it doesn't work? – chance Nov 4 '14 at 5:14
  • @chance The same way as before: sudo nvram -d boot-args Or reset the PRAM. – rwg Nov 4 '14 at 6:37
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    This works once you boot. But only until the computer goes to sleep. Waking it back up turns the built-in display back on. – Fydo Dec 14 '14 at 19:28
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    1) After putting in the terminal command, reboot and close the lid immediately 2) Keep the lid closed during boot up and once logged in, open the lid 3) The MacBook Pro's screen is off – Ryan Heitner Jan 3 '15 at 17:25
  • @RyanHeitner 3 steps work fine! If you need a solution for sleep&wakeup, please visit OSXdaily-Post with Section "Disable the Internal Laptop Display in OS X Yosemite" a hint to correct wake up procedure. Have fun! – andreas-supersmart Mar 24 '15 at 11:53
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Found this wonderful free application :

https://github.com/Eun/DisableMonitor/

Works like a charm. Warning: The app is not in development anymore and warns that it might cause irretrievable dataloss.

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    This application reduces the brightness of the monitor to 0, but it remains on! So probably it consumes more. Is there a way to completely turn off? – Fred K Dec 18 '15 at 10:15
  • If you choose to mirror the external display (not add a separate desktop) this should reduce the workload – Nir Golan Jun 14 '16 at 7:55
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    @FredK After the display was disabled, it won't allow me to move the mouse to the disabled display anymore (expected result), turns out it does more than reduce the brightness to 0. At least the expected results are archived. – Mengdi Gao Dec 5 '16 at 1:41
  • @MengdiGao Only if you equate "can't move mouse to" with "turn off display". – Andreas Dec 30 '16 at 16:45
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I have a magnet iPhone case, I put it near my old macbook's keyboard, near the ASDF keys, and the internal screen turns off immediately! It's so simple!

Credit to http://www.cultofmac.com/176329/turn-off-internal-lcd-display-of-your-macbook-air-os-x-tips/

Edit: You have to connect your macbook to a power adapter to make this method working.

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Similar to other posts here, I ended up doing this with a fridge magnet. Flexible plastic ones did not work reliably, so I found one with a small (~5mm diameter) circular metal magnet on the back. Hopefully this matches the magnet in the lid fairly well, and won't overload the hall effect sensor, if that's possible.

To pinpoint where to place the magnet, I used this guide:

https://www.ifixit.com/Answers/View/506016/Putting+to+sleep+with+a+magnet

This places the sensor close to the left-hand edge, near the headphone jack.

Waved the magnet over the area and if the magnet is strong enough both displays will turn off and the external one then comes back on by itself. When I lift the magnet more than 1cm away from the case the screen comes back. This seems about right compared to the actual lid.

Hope this helps someone, will post an update if anything goes wrong!

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Go to screen saver then activate the "display off" in hot corners.

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    Both monitors go offline in this case. – Shmidt Feb 6 '16 at 6:21
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Reducing screen brightness to 0 via the keyboard works for me - Macbook screen is totally dark, but the external display is not affected.

My use case is watching a movie on an external display and wanting the Macbook monitor totally off. If you want to make sure the trackpad can't go off the external screen (to the darkened Mac screen) just choose to Mirror the displays and then what you see on the external monitor is all there is.

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  • Welcome to Ask Different. We like answers to be more than just a single line. Ideally, you want to explain why your answer is *right." It also helps to provide links, citations, and/or screen shots. Please review our help section How to Answer on writing good answers to questions – Allan Aug 13 '16 at 21:02
  • This works to not have any distractions on that display, but osx still sees it, in the sense that you can still move your mouse and apps to that display, even though you can't see it. – Steve Heim Feb 8 '17 at 7:54
  • @SteveHeim Right - it doesn't disable the screen in a programmatic sense, I see that the original question was concerned with GPU. This fits my need when watching a movie for example. – Freewalker Feb 8 '17 at 17:37
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This trick works (make the external monitor as primary one and partially close the lid till display goes off)

http://gizmodo.com/5938452/a-trick-to-make-using-an-external-monitor-with-your-macbook-way-better

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    While this link may answer the question, it is better to include the essential parts of the answer here and provide the link for reference. Link-only answers can become invalid if the linked page changes. – Tetsujin Aug 16 '15 at 15:42

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