Turn off MacBook Pro's display while connected to external monitor on Yosemite

Question

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?

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
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 02:47
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
Some lateral thinking: Use a magnet to trick the MacBook into thinking the lid is closed. "Use at your own risk" yada yada. — Steve Moser, Feb 18 '16 at 15:15

score 19 · Answer 1 · edited Jul 10 '21 at 22:46

19

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.

edited Jul 10 '21 at 22:46

grg

201,078

answered Jun 25 '15 at 00:24

prototypical

299

2

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 07:55
4

@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 05 '16 at 01:41
@MengdiGao Only if you equate "can't move mouse to" with "turn off display". – Andreas Dec 30 '16 at 16:45

score 13 · Accepted Answer · answered Nov 04 '14 at 04:27

13

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.

answered Nov 04 '14 at 04:27

rwg

146

How do we remove this command if it doesn't work? – chance Nov 04 '14 at 05:14
@chance The same way as before: sudo nvram -d boot-args Or reset the PRAM. – rwg Nov 04 '14 at 06:37
1

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
1
After putting in the terminal command, reboot and close the lid immediately
Keep the lid closed during boot up and once logged in, open the lid
The MacBook Pro's screen is off

Ryan Heitner

Jan 03 '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

Works on mack book with nvidia graphic cards, potentially need to switch to "better performance" in the Energy Saver settings to switch to your nvidia graphic card (like on my 2009 Mac Book Pro) – Ronan Quillevere Jun 23 '15 at 08:53

Thanks for this! Also according to your findings the command pre-yosemite should be "iog=0x2" since otherwise you're setting FBVLThrottle to 0 which caused an issue for me with my monitor. – 1110101001 Feb 26 '21 at 22:09

As others noted, this also unfortunately gets lost when the laptop goes to sleep and wakes back up. I spent a little bit of time tracing through the iokit hierarchy, and it seems like this is how it's structured:

kIOGDbgLidOpen controls whether we should reprobe on lid open event
When the lid is closed, seems like internal (backlit) display is not present in iokit hierarchy at all. "Clamshell" mode is nothing more than this fact along with a iopm setting to prevent sleep when the lid is closed.

– 1110101001 Jun 07 '22 at 03:53

The reprobing is done by AppleGraphicsControl which is not open source. It's not clear to me how exactly this works, but I assume upon receiving the request something goes through the attached outputs and creates an IODisplay for each of them. Conversely, in clamshell mode something must prevent the IODisplay being created for internal.

Unfortunately I think this means it's basically impossible to disable internal display at the lowest level unless someone wants to disassemble NVDA driver to figure out what happens during a reprobe event and how the IODisplay is being created.

– 1110101001 Jun 07 '22 at 04:14

Seems like the probe gets routed to IONDRVFramebuffer.cpp. I think that's about as far as I can trace just reading the code, seems like from then on it gets to driver-specific things.

And of course note that we can't just noop the probe because upon a wake from sleep we need to discover the external monitor as well.

– 1110101001 Jun 07 '22 at 04:36

FrankCJ · Answer 3 · 2017-01-22T19:41:22.580

4

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.

edited Jan 22 '17 at 19:41

answered Jan 22 '17 at 11:18

FrankCJ

41

score 0 · Answer 4 · answered Mar 21 '19 at 16:36

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!

score 0 · Answer 5 · answered Jan 06 '22 at 09:41

0

Lunar can turn off the MacBook display without having to close the lid of the MacBook.

This allows the MacBook to cool down faster and allows you to keep using TouchID, webcam and the very nice speakers of the MacBook, while being able to focus on the external monitor.

The feature is called Blackout, here are some more details: lunar.fyi/#blackout

How it works:

Sets the native brightness of the MacBook display to 0
Sets the Gamma tables of the MacBook display to a list of zeroes
Mirrors the external monitor to the MacBook display so that:
1. The monitor keeps its native resolution
2. Apps/windows don't get trapped on a non-visible display

To activate, just press Control+Command+6 and Lunar will toggle Blackout and do all of the above steps for you.

Disclaimer: I'm the developer of Lunar and BlackOut is a paid feature with a free 14-day trial

answered Jan 06 '22 at 09:41

Alin Panaitiu

822

what is the difference with DisableMonitor? – netawater Apr 12 '22 at 12:43
@netawater the functioning principle is the same as with DisableMonitor: a screen is disabled by fading it to black and switching it to mirroring mode. – Alin Panaitiu Apr 12 '22 at 14:14
The main difference is that Lunar can also disable the built-in monitor automatically on external monitor connection which is what most people want.
Lunar also provides hotkeys/buttons to completely power off external monitors using DDC or even disable all monitors but the one you're working on at the moment.

Here's a picture showing most of what BlackOut can do: BlackOut options
– Alin Panaitiu Apr 12 '22 at 14:20

score -1 · Answer 6 · answered May 22 '15 at 04:10

-1

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

answered May 22 '15 at 04:10

user128876

1

3

Both monitors go offline in this case. – Shmidt Feb 06 '16 at 06:21

Freewalker · Answer 7 · 2021-07-13T16:03:13.587

-1

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.

edited Jul 13 '21 at 16:03

answered Aug 13 '16 at 19:31

Freewalker

363

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 08 '17 at 07:54
@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 08 '17 at 17:37

score -3 · Answer 8 · answered Aug 16 '15 at 15:35

-3

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

answered Aug 16 '15 at 15:35

chan

1

3

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

Turn off MacBook Pro's display while connected to external monitor on Yosemite

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