Mac External Monitor Ripple

We recently experienced a very odd ripple on our Mac Mini External Displays (both Dell Models) when you dragged windows across the screen(s) and wanted to share with you possible solutions.

  1. First off check for possible causes of interference. Is there a power drain on your Mac, with say USB ports, or is something incorrectly set up?
  2. If you have ruled out the above then you may need to enable ‘subpixel font rendering on non-Apple Displays’ and to do this simply open Terminal and type/copy&paste the following command:-
defaults write NSGlobalDomain AppleFontSmoothing -int 2

Now reboot your Mac and hopefully the issue is now resolved.

Update for OS X Yosemite (Oct 2014)

The same screen ripple  issue happened  after upgrading an an older Apple Mac Book Pro (MBP) to Yosemite and we found that the above code also fixes this issue.

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A highly experienced Web Designer / Web Developer (Webflow, WordPress, Weebly & Custom), Front-end / Back-end Developer & New Media Specialist, with extensive knowledge of a wide spectrum of technologies in the Development and Creative Industries, built up over a number of years.