Realtek no sound in left speaker or subwoofer using Altec AVS300 speak

System - Windows 7 Professional 64 bit
Motherboard - Gigabyte GA-880GMA-UD2H
Sound - Realtek on motherboard
Speakers - Altec AVS300

My problem is that I cannot figure out how to get sound playing from my left speaker and also the subwoofer. It worked fine on my previous Win XP system.
As far as I can tell only the right speaker works.

The Altec systen has 2 speakers and a subwoofer with 1 leads that plugs into the motherboard. I used the Green connector on the back of the motherboard.

The realtek HD Audio Manager does not a a 2 speaker plus subwoofer configuration.

Any help would be appreciated.

Thanks.

I think your stereo cable has the problem, try connect with your TV or ipod and see if both speakers and subwoofer are working or not. If not, then you may have to buy a stereo cable. Hope this helps :)