Zalman ZM-F1 80MM Cooling Fan You can choose the mode of operation (Silent/Normal) 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 34.2 dB