Win7 not showing anything but 2ch as a supported format

I have an HTPC connected to my LG LH5590 LCD/LED TV via HDMI cable. I have my surround sound system connected to the TV with an optical cable and my PS3 and DirecTV reciever are both connected to the TV via HDMI cable. My TV properly passes through Dolby Digital 5.1 for the PS3 and the DirecTV receiver, however, all my HTPC sound card config will show me for supported formats is 2ch. Sound works great in stereo but I simply cannot get the HTPC to offer 5.1 as a supported format.

I have downloaded the latest realtek driver for my onboard sound card but still no luck. This sound card definitely supports 5.1 and 7.1 so that is not the issue. Any ideas? Thanks in advance for any help you can offer.