I'm using an external monitor for my 2015 Macbook Air. I don't want this thing to overheat, so i open the lid so heat can escape upward. However, that puts everything back in 2-display mode, using more graphics card / RAM to drive that second screen, which works against my goals.
I can press CMD+option+eject (on my apple bluetooth keyboard) to turn off both screens, while the computer keeps running. How can i do this to just one screen?