The 990's DVI switching is bit-transparent for HDMI as well as DVI: it does no processing or manipulation. DVI actually can handle more bandwidth than HDMI for video, if you use dual link. Most of us use single link since that's sufficient for resolutions up to 1080p, and it is DVI single link that HDMI used as the basis for their video signal. There were problems with some earlier HDMI chipsets that didn't play well with DVI (losing whiter-than-white and blacker-than-black), but that has been resolved in newer products and the 990 never played a role in those cases anyway - you could connect an HDMI source to an HDMI display through the 990 and lose no data.