Whatever fans the Thermaltake M9 case comes with are literally silent. I can't hear them easily. They sound like they are 2db or something.
The noisy CoolerMaster fan was installed on the side panel, I took it out and put it on the top of the case as "top exhaust" fan, now the noise is gone. It must have been vibrating or something while installed on the side panel.
Yeah, it helps alot if you put rubber washers on the fans.
I am going to echo the other skeleton face up there....johnnylucky on the silentpcreview site recommendation. Though I can say that I really like these fans which that site hasn't reviewed as yet.