Are you running a long cable? And it might help to upgrade to a better cable with better shielding or you might need a video ampflifier if is it a long cable run.
Did you try running the video out to your TV and see if it has interference. In to the TV card, out from your video out on your video card to TV. ASUS is kinda new to the TV card thing.
I find Hauppage and Pinnacle very good TV tuner cards, or maybe the card is bad or maybe some settings. I have never seen that problem and I have been using TV Tuner cards for years.
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