Mac OS X and Dell Monitor via HDMI

Please refer to here for issue background details. Below is just steps for El Capitan running on Retina MBP with Dell U2410/U2414 monitors.

  1. Download the patch-edid.rb script from Andrew Daugherity’s improved patch-edid.rb script. Put the script on Desktop.
  2. Connect the external monitor.
  3. Type “cd Desktop; chmod +x ruby patch-edid.rb; ./ruby patch-edid.rb” in Terminal.
  4. A new folder will be created on desktop. Move it into the “/System/Library/Displays/Contents/Resources/Overrides/” folder. If prompted if you want to overwrite an existing folder, consider backing it up first.
  5. Restart Mac. The monitor should changed color mode to RGB.
  6. Optionally, Adjust the color profile inside Mac OS and/or monitor presets as needed.