i just built my first rig. i have the msi 785gtm-e45 mobo 2gb crucial dual channel 800mhz ram. with the on-board sound. i have a 5.1 surround sound system i want to use. and its hooked up. the only speakers that is working are your front side two. the front speaker the sub and the back two do not work. i have tried to configure my sounds in the control panel. and still nothing.i really need some help please.