The Noctua NF-S12 and the NF–R8 Silent fans Review
 

Today I shall be taking a look at a product from Noctua that
promises to be the answer to those seeking that silent dream. The
Noctua NF- S12 and the NF – R8. We only got one NF – S12 (120mm) as we
know most 120mm fans can be run silently, but on the R8 we decided to
get 3 of these in to replace a complete set of fans in one rather loud
UV acrylic case. Trust me even with the quiet golf ball fan there is
still a slight hum of fan noise, so let us see if the Noctua’s can
give me even more piece and quiet shall we.

http://www.xtremecomputing.co.uk/review.php?id=368