I just installed a new Sapphire Radeon HD 7950 video card into my Mac Pro (5,1 mid-2012). It works great, except occasionally, perhaps once every hour or so, the screen flickers. By "flicker" I mean that the entire image becomes garbled for just a fraction of a second and then returns to normal. The card's single dip-switch is set for Mac compatibility. No other video card is installed and I'm only running a single 30" Apple Cinema HD Display.
Does anyone have any idea what might be causing these occasional "hiccups" and whether it is something that can be stopped?