Your product specs says that unit originally came with Crystal Audio Chipset located on the MoBo.

"If computer does have onboard sound, do the following to disable it:

1. Turn on the computer and press F1 at the blue HP screen. "Entering Setup" should appear on the screen.
2. In the Setup screen, press the LEFT and RIGHT ARROW keys to highlight Advanced.
3. Press the DOWN ARROW key until Onboard Audio Options, or I/O Device Configuration is highlighted, press ENTER.
4. Press the DOWN ARROW key until Onboard Audio Codec or Audio Codec is highlighted, press ENTER.
5. Press the DOWN ARROW key until Disabled is highlighted, press ENTER.
6. Press F10, then the Y key, and then ENTER to exit."

The previous quote came from HP Pavilion Desktop PCs - Replacing a Sound Card.

Hope this all helps you out...Good Luck!