I have been upgrading several brand new TiVo Premieres and noticed that in almost every case the fan vibrates causing a noticeably high pitch hum which is much easier to hear than the whirling noise caused by the fan. Also, on a few the top cover itself vibrates causing a similar high pitch noise. You can check this by slightly pressing down on the back edge of the top cover from one end to the other. I can hear both in a completely quiet room with the TiVo roughly twelve feet away and my hearing isn't the best (by far). I spend endless hours in the room (without any other noise) which is why it is bothersome. If both high pitch noises are absence I can't really place the TiVo in the room (hear it uniquely). I have noticed both of the above before swapping drives so it's not my lack of talent in taking the cover off and replacing it. Now if you appear to be bothered by either I can suggest trying a few things... Top cover vibrates Loosen the four screws slightly If that doesn't help take the cover off and place painter's tape along the back edge of the inside of the cover. Fan vibrates Loosen the four mounting screws and reposition the fan to see if it stops vibrating (if so tighten the screws holding it in place). If that doesn't help take fan out and place a small piece of painter's tape on the bottom of the fan and one on the middle of the fan where there is a round piece of metal (it pushes against the case). Doing the above has cured both conditions however I have had to adjust the fan's screws once or twice afterwards. But once resolved they have remained pleasantly quiet every since. Of course don't do any of the above as I'm sure you'll void your warranty and or zap yourself.