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Using a Mass Airflow Sensor to correct for altitude or airflow variations in computer system cooling designs Disclosure Number: IPCOM000033493D
Original Publication Date: 2004-Dec-13
Included in the Prior Art Database: 2004-Dec-13

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Typical computer cooling solutions employ temperature feedback to regulate the speed of the fans. As either the in-box or ambient temperature varies, a control circuit varies the fan speed to compensate. However, temperature is not the only variable that affects the system cooling performance. At high altitudes, the fans must rotate faster than they would at sea level to move the same mass of air. This increased fan speed leads to more system noise. Since current cooling solutions employ no mechanism to determine air density or altitude, the system fan speed must be calibrated to assume that they are operating at high altitude. This results in the system fans spinning at higher speed and creating more noise at lower altitudes than is necessary. As system airflow demands increase, it becomes more important to regulate accompanied system noise output to meet workplace standards. This article describes a mechanism to use a Mass Airflow Sensor to modulate fan speed in a server or Blade chassis thereby cooling the system more efficiently.