I am using Mountain Lion on my MBP, my external TFT monitor used to work great at its native resolution (1920×1080) when connected to the MBP.
However today after shutting it down and powering it up the resolution on the external monitor was on 800×600. In system preferences the 'Best for Display' resolution output was selected (wasn't that supposed to be 1920×1080?) when I clicked 'Scaled' and chose 1920×1080 the resolution indeed changed, however it is not taking up the whole screen. There are 1 inches to the left and right of the monitor that are not being used. Its as if the viewport is "shrinked".
I tried downloading SwitchResX but it did not help, when choosing 1920×1080 again the viewport is missing about an inch to the left and right.
Any thoughts?
Best Answer
I had precisely the same issue, and so did this poster: External monitor randomly lowers resolution adds black borders
the answer in both cases was to switch out the VGA cable.