Installing a soundcard on an Alienware Aurora S6

I just brought a new Alienware Aurora S6 computer. I'm not satisfied with the sound on-board and would like to install a new soundcard, the Asus Essence STX II 7.1 soundcard. The soundcard need power through a Molex power connection. I have tried to install the soundcard, but I cannot find any Molex power connections inside the computer. From can I get the power and do I need a special internal powercable?