I use them to make almost inaudible to my water-cooled PC. For this I use 2x 120mm (BL030) on the radiator and 1x 140mm (BL031) as a case fan.
The attachment of the 140mm fan carried easily within about 2 minutes with the supplied plastic pins. The 120mm fan can be screwed onto the radiator NOT with the thick housing screws of course, but the brackets for the plastic pins are also very good to thin screws (eg M3x30mm) hindurchzustecken. Something more stable compounds than with the plastic pins can be made, but still probably slightly better noise decoupling of rubber fan holder are used over the Plastikverschraubung simultaneously.
In standard operation without special load (120mm at about 800 rev / min, 140mm at about 480 rev / min), the fans are quieter than the housing PSU (Corsair TX650W) at maximum load (120mm at approximately 1330 rev / min, 140mm at about 600 rev / min), they are still barely audible. Only the case of manual control of the PWM at 100% (120 mm at about 1580U / min, 140mm at about 1010U / min) all produce a clearly audible noise air, but the bearings do not generate additional noise.
