What exactly do you mean by "sound activated"? When the lights detect a sound they turn themselves on? When the sound goes off they turn themselves off again?
Not sure this is possible to buy for a computer? Where would the sound come from? The lights would only be able to turn on if the computer was already powered on, which brings the question why not just get lights with an on/off switch rather than sound activated?
Clap on Clap off lights are about the only sound activated lights I know of, and these tend to only be used in houses as a main light for the room. Expensive.