How to Turn Off the Internal Speaker in a Dell Computerby Daniel Hatter
Certain Dell computers, such as the Optiplex, can include built-in internal speakers. Internal speakers eliminate the need to purchase and install external speakers, which can save a decent amount of desk space and setup time. If the internal speakers on your Dell computer aren't loud enough or of high-enough quality for what you need, you can turn them off and use external speakers instead.
Click the "Start" button and click "Control Panel." Select the "Hardware and Sound" category and click "Manage Audio Devices" in the Sound section. You will be presented with a list of all audio playback devices (i.e., speakers) connected to your Dell computer.
Right-click the internal speakers' device listing (the default name is usually "Speakers" or "Internal Speakers") and select "Disable." Click "Apply" and click "OK."
Plug the audio cord from your external speakers into the audio-out port on your Dell computer. This port will usually be green and labeled with an icon of headphones or speakers. Your Dell computer will recognize the new speakers automatically and they will be used as the default speakers.