I'm using 120mm PC fans to
increase the airflow over my heating system's radiators. Some of the fans have become too loud - I'm assuming the bearings are worn, as I clean the dust off twice a year. I'd like to replace them with fans that will be both quiet and efficient (best airflow at lowest current draw), but from looking at a few I see that quiet just means lowering the rpms, which also reduces the airflow.
Are there any particular designs I should be looking for? Number of blades, special blade shapes, bearing types, etc.? 140mm fans are too large, unfortunately
