How do I stop the beeping noise that happens when I turn on my Dell laptop?

to be more specific, my laptop is an alienware M17x. When I turn it on WITHOUT the charger plugged in, two beeping noises accompany a screen of text. At the bottom it says something about my AC adapter not being plugged in and that it is going to switch from discrete graphics. I can press F2 for setup. What do I do to stop this noise? I can't have it making that while I'm at school. Thanks!