Could be a bad sound cable. The analog/digital cable the goes to your optical drives and or other IO devices that use it. Also you can check the connections themselves to make sure they are clear of dust. Have you tried updating the drivers for the soundcard? Is it possible that its your speakers not your soundcard? Sometimes a new dedicated soundcard is the way to go. I got my Sound Blaster Audigy 2 ZS for about $120 but that?s a real good soundcard you can find a decent one for $30