Corsair Air Series AF120 Quiet Edition High Airflow 120mm Fan. Air Series AF case fans perform best in unrestricted spaces with at least 3 cm (1.2) of clearance, and theyre ideal for mounting at the rear or top of your PC case as exhaust fans for your PCs motherboard and CPU, graphics accelerators, and other components that fill the case with heat. They work equally well as unrestricted intake fans for areas like side panels or bottom intakes.