[locomoco]

Anyone know how to turn off the Macbook pro screen with the lid open while using external monitors? On Mavericks this worked just fine:

http://gizmodo.com/5938452/a-trick-to-make-using-an-external...

Now no dice... anyone know a way to keep the screen off with the lid open?

To execute in Terminal:

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

To undo in Terminal:

sudo nvram -d boot-args

Once you type it into terminal I believe you need to enter your password. I then restart my machine. Now the TRICK is to either restart your machine with the lid already closed (hit restart then slam the lid!) OR turn the machine on for the first time (then quickly slam the lid!) once you are past the login screen you can open the lid.

[wodenokoto]

Can't you just turn the brightness down to zero?

[locomoco]

Yes, but it's not the same as turning the display off. The GPU is still outputting signal to the Macbook Pro screen.

[nkurz]

Wow, I hadn't considered that. It might explain why I get terrible battery life when playing movies on a TV over HDMI with the screen "turned off" by dimming it down to zero. Thanks for the hint.

[locomoco]

Along with the battery suck, it also generates more heat as the GPU has to output 2 signals.

[Karunamon]

what the.. why? The screen is unusable without the backlight.

[jevinskie]

Perhaps latency? Suppose it takes 0.5-1 second to switch between "Off" and "Lowest brightness" when turning On/Off the GPU, that could create a bad experience when every other brightness change is instantaneous. Though it is a great power optimization idea, if the (unknown to me) downsides aren't too bad!