The OS X GUI has a standard refresh rate of 60 Hz. I doubt that the Retina iMac uses less.Hm, you're right, sometimes it doesn't say apparently. I'm 95% sure it's running 60 Hz, but it would be nice to get that confirmed.. Sadly I don't know how to check that either . Maybe some gpu test has a "enable vsync" option that will lock the framerate to the display refresh rate, but otherwise I'm out of ideas. Anyone else know?