I basically leave my MBP on 24/7, I just find it more convenient, and often I will render something over night. I've started to notice that occasionally if I leave my computer on for a few days, I hear a fairly loud humming noise. The only way to make it turn off is to restart the mac and then it will go away for a few more days. Does anyone know what may be causing the noise? Also is it bad for the hdds if I put my Mac to sleep and wake it up a lot? Usually when I move it from room to room I just close the lid, but then 30 sec later or so I'll just re-open it, is that bad to keep doing that? Thanks for help.