Troubleshooting Windows Sound
What happens when you have the sound card installed, but you're not getting any sound or if your computer doesn't show the default sound device?
The first thing you should check is that you have plugged in your speakers in the right connection. Depending on the type of sound card, there should be an audio connection that is colored pink. This is to help when having multiple components plugged in to the sound card, such as a subwoofer or a microphone. The speakers that you connect to your computer may or may not also be color coordinated; it all depends on the speakers. Make sure that your speakers are on as well.
If you find that your speakers are plugged in correctly, go into the computer's properties and find the device manager. Depending on the operating system, you will either be able to directly type in the term 'device manager' (in the case of Windows Vista or Windows 7) or by right clicking on My Computer, selecting properties, and going to the tab that says 'hardware'.
The device manager will be the second option. In the device manager, first look for anything that is has a yellow exclamation point or a question mark. This is usually an indicator that there is a hardware problem with the device. In most cases, the device driver either needs to be installed or perhaps updated. Depending on the sound card, you should be able to locate drivers on the manufacturer's website. Download them and then install them; you will often be prompted to restart your computer.
If the device manager has a listing for both sound cards, you can disable one by right clicking on the name of the card (usually the manufacturer) and selecting disable. It is recommended that you know the name of which sound card you plan on using as your default.
For more information, check out this article on how to get rid of computer speaker static.