I am running OS X 10.8.5 with an external monitor, and whenever I close the lid of my laptop it automatically goes into clamshell mode so that all the screen contents switch to the external monitor.

When I was running OS X 10.6.8, the machine will go into sleep when I close the lid so that the external monitor goes blank.

What setting(s) should I change in 10.8.5 to bring back the 'sleep' behavior?


Try the folllwing:

1) disconnect external monitor

2) disconnect power cable

3) run this line in Terminal: sudo nvram boot-args="iog=0x0"

4) restart

5) plug back in external monitor and power cable

  • It turns out that simply unplug the power cable before closing the lid will put the machine into sleep. Also, once it's asleep, you can plug back in the power cable, and doing so won't wake up the machine. – MLister Aug 18 '14 at 9:20

I had this issue too, and came up with this script that monitors your lid state and puts the machine to sleep when lid is closed: https://github.com/pirj/noclamshell

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