The Sanyo Denki SANACE 'silent fans' are the lowest noise, highest airflow ,dual ball bearing fans, and are available from Farnell.

Not just standard fans run at low speed, these fans offer exceptional performance, by combining a new impeller and motor design with precision tuning and balancing of compents to produce a low vibration low noise fan which will offer the same performance over it whole life.

 

For example the the 9S1212L40119S1212L4011 fan sold under Farnell 1755876

Is a 120mm 12V fan with a flow Rate:48.1cu.ft/min  and a typical noise figue of 17dBA