That SupremeFX "sound card" is the onboard sound. It isn't a true sound card and nothing more than a riser card containing the onboard sound.
I would start with contacting where the board came from and see if they still have the card. failing that you can order one from Asus for $45.00, Supreme FX X-Fi
Personally if you can't get it from where the board came from I would go with an actual sound card.