The first thing I notice, looking at your specs is the "NVIDIA High Definition Audio". That would be incorrect if you are trying to use the Motherboard's built in sound device (probably RealTek or IDT). NVIDIA HD Audio is the HDMI audio output and that is ONLY for the HDMI output, not the PC's speakers.
Check the Control Panel/Hardware and Sound and finally the Sound Panel. Your "Speakers" should be set ast the Default Playback device. This is the first step.