Helo , i experienced the same trouble on 7 diferent machines, where all machines has the same hardware:
i7 3930k , Asus sabertooth X79 , 32GB memory corsair 1866Mhz , SSD Adata ,VGA ATI HD6990, Power Supply Corsair TX850M, 01 Vision RGB E2S, 02 Blackmagic intensity pro , 01 Blackmagic Decklink Duo, OS: Win 7 64 bit.
But one thing is very curiously , the horizontal stripes just apear when more of 3 outputs are in use, and when i turn on the deinterlace the problem stops , but the image of capture is not fine, in video motion ok , but in smaller letters on Powerpoint the result is very bad!