Except I don't know of any video cards that transfer sound as well. A lot of video cards have S-Video ports, and S-Video is capable of transferring sound, but because the video card is not, you have to hook up audio cables as well.
EDIT:
I take that back... your card has built in 5.1 HDMI audio, so if you just plug it into your TV sound should come out the TV speakers along with the video.