My guess is that sound card isn't a real 5.1 surround card. The card on the site shows only 4 jacks on it. One is an input, and one is a mic, so that only leaves 2 for your speaker, front and rear. Mine has the extra jacks. My TurtleBeach head set has 4 jacks. One for the mic, and the others for speakers, and so does my sound card.