Enlight EN-5601500 COMBOSPY PC Fan Speed Noise Silencer - Controls 4x Cooling Fans (Retail Box Beige Face Plate) Intelligent computer cooler and silencer - adjust fan speed optimally. Full speed manual bypass mode allows instant maximum cooling. Fits in a standard 5.25" drive bay while making an 3.5" drive bay in its back available for hard drives with undermount screw holes. Standard 4-pin power connector with a bypass connector - works with any system configuration with any power supply. Include 2 thermal sensor probes to detect temperature at the exact spot you need. Micro-controller will automatically adjust system fan speed to minimize fan speed to minimize fan noise while achieving user configured temperature range.