I have a PC Clup/Enpower laptop that is equivalent to an ASUS M5200N. I've noticed a quiet, buzzing noise emanating from the bottom of my laptop, even when the laptop is turned off (and the AC adapter is disconnected). The noise is not strange; it just sounds like some part of the computer is still on. The sound seems to be coming from the laptop's underside grating near where the fan is (please pardon my terminology ignorance). The fan is off (I can see that the fan-blades are motionless and there is no air blowing), so I don't think this is fan-related. The noise persists for hours after the computer is turned off. When I turned it back on after 8 hours, the battery was down to 75%. The noise stops when I remove the battery pack. Does anyone know what this might be? Is this a normal operation? I checked my Dad's HP laptop and my brother's Dell, and neither laptop does this.