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?

1 Answer 1


The "hiccups" could be due to poor cables. Previously I have seen that result in these "flickers" that come randomly once in a while.

Replace the monitor cables with properly shielded, quality cables!

  • I hadn't thought of that. I will try and report back Commented Sep 26, 2018 at 0:42

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