I dont know how to describe it but like the macbook rev. a's it has a faint mooing noise. Its not loud or anything but when your in a dead silent room you can hear the silent revving up and down gently of the fan of the ati 3870. Kind of like a mooing sound but a bit higher pitched than what the macbooks sounded like I guess. It is only apparent in dead silent room and when your playing something intensive like a 1080p movie other wise during normal usage the card is dead silent. Anyone else noticing this too?