It is VERY quiet all the time. In over a year of use, the fans only came on a few times, as the temp only exceeded 65 a few times despite heavy usage. Even with fans on, it is very quiet. If you listen very closely, you sometimes hear odd sounds from the drive --- plink or plonk type sounds. I once read they are normal. Overall, you never hear this machine running, unless your ear is practically resting against it.