I have had my pro for over a week now, and has been quite satisfied with it so far except one thing. while using it in a quiet room, there is a constant humming noise coming out from top of the machine where the vent is. its very high pitched and subtle and is only audible in a quiet setting. it sounds like electricity circuit humming. also, the noise can be picked up by the internal mic while using Skype. my surface rt is completely quiet compare to pro. even my MacBook pro is quieter. reading reviews online most commented surface pro is quiet, so that makes me wonder if I have a defective unit. does anyone noticed the similar high-pitched humming noise coming out from the machine?