be quiet! Silent Wings Pro 4 140mm PWM, 2400 RPM, Premium Cooling Fan, 4-Pin - BL099

Product Features

• Optimized fan blades for the highest performance on radiators and heat sinks
• Speed switch allows changing maximum PWM speed between medium-speed, high-speed and ultra-high-speed (up to 2400 rpm)
• Small tip clearance and a fan frame with a funnel-shaped air outlet for extremely high air pressure
• Virtually inaudible operation at regular speed
• 6-pole fan motor and fluid-dynamic bearing for less vibration and very smooth operations