I have a MacBook Retina.

Whenever I attach a secondary screen, projector or monitor and select the "Mirror Displays" option, the secondary screen turns all black.

It does not matter what connection I use. I've tried the following, and they all have problems:

  • MiniDisplay port to a Cinema Display
  • HDMI to HDTV
  • MiniDisplay -> VGA/DVI converter -> projector

It does not matter what resolution I use.

It all started after connecting it to a projector, where all other presenters using PC was having similar problems.

1 Answer 1


I solved the problem by resetting NVRAM / PRAM:

  1. Shut down your Mac.
  2. Locate the following keys on the keyboard: Command (⌘), Option, P, and R. You will need to hold these keys down simultaneously in step 4.
  3. Turn on the computer.
  4. Press and hold the Command-Option-P-R keys before the gray screen appears.
  5. Hold the keys down until the computer restarts and you hear the startup sound for the second time.
  6. Release the keys.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .