Full Details from Amazon.com : http://www.amazon.com/gp/product/B000292DH2?tag=onigi-20
Zalman ZM-F1 80MM Cooling Fan
You can choose the mode of operation SilentNormal by utilizing the Noiseless Connector RC56
Does not generate noise or vibration in Silent Mode
CPU video card or mainboard chipset can be cooled to a temperature sufficiently below the temperature required by the manufacturer in Silent Mode
Speed - Silent Mode 1700 RPM Normal Mode 3000 RPM
Noise Level - Silent Mode 20 dB Normal Mode 342 dB