There is a 140mm fan on the bottom of this power supply. Unique to the QFan series of Toughpower power supplies is the QFan within the power supply. It has an almost frameless design with a special blade design as well. Both of these features are supposed to make this power supply quiet. During testing, at idle loads, this fan is whisper quiet, which is great for a 650 Watt power supply. With loads, the fan slowly sped up to what I would call a medium speed, which was still pretty inaudible.