How to Disable the Laptop Screen in Lion, when running an External Display

In Snow Leopard, it was possible to have your laptop open, running an external display, but have the laptop’s display off. This had the big advantage of all the GPU power being used to run just the external monitor, and also meant that you could run your external at its native resolution. But for some strange reason Apple disabled this feature in Lion. So now the only way to do this was to close the lid on you laptop… which often results in over-heating. Thus to get back to the joys of a cool laptop and open that lid, use this following hack, which was posted on the Apple support forums by user chenga.8.[Macworld via Apple Discussions].

To go back to pre-Lion behaviour enter the following command in Terminal:

sudo nvram boot-args=”iog=0×0″

To undo this change type type the following command or zap the PRAM (press Cmd+Opt+p+r at power up):

sudo nvram -d boot-args

Woo hoo, and a big thanks to chenga.8 for the fix !