At work my speakers are connected to a onboard sound card. A couple months ago I started to have a problem where the sound wound make a load poping/beeping noise. The sound would be fine but out of the blue would make the poping/beeping sound and the poping/beeping would repeat, turn speakers off and try the next day and noise would come back. What would couse the speakes to make a nasty noise? Could it be the onboard sound card or the speakers?