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.
ANSWER :
Found the solution here: https://apple.stackexchange.com/questions/152203/osx-10-10-yosmite-turn-off-macbo ok-pros-display-while-connect-to-external-moni
In terminal:
Enable: sudo nvram boot-args=”niog=1″
To undo: sudo nvram -d boot-args
This works brilliantly!
Steps I use:
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