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.
- 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?
- 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.