Audio in Windows

how do you have your speakers connected?
and is any audio coming out of the speakers?

Start Menu -> Control Panel (switch to classic view) -> Sounds & Audio Devices

you can select what type of speaker set up you have, and what audio line its coming from.

Line-Out port? - It should auto default out there, and should mute the internal speaker from that point.

Headphone Jack? -> this usually silences any other audio input device for the most part.

Optical? -> if you have optical youre going to wand to lower the Master Volume; double click on the volume icon in the task bar and dont mute it, just lower the volume all the way down as optical has its own volume control.

 

in windows you have to have your speakers plugged into the HEADPHONE jack as it will not come out in the back audio jack i think its still a driver error or something but my mac pro is the same way.