The Alphacool ES fans were specially developed for use in servers and workstations and, unlike usual, do not offer a 2 or 3-pin DC power connection, but a 4-pin PWM control. PWM control Instead of using the usual 2 cables or the 3-pin connection, Alphacool now also uses a modern 4-pin PWM connection for its enterprise fans, which is supported by more and more server mainboards. The fan always receives full voltage via the 4-pin PWM connection and is controlled by pulse width modulation. This allows the fan to be controlled over a significantly larger speed range. Double ball bearing unlike classic plain bearings, the Alphacool ES fans have a double ball bearing for an increased service life under full load. Double ball bearings are generally considered to be the highest quality bearings in terms of durability and quality. This also ensures smooth running with minimal vibrations. Protective circuits All Alphacool Enterprise fans have several protective circuits. If the fans are blocked, they automatically try to restart at reduced speed after a few seconds. Thanks to the gentle start, including the emergency start function, the fan can be blocked for up to 72 hours without suffering any damage. If the polarity is incorrect when connecting, the electronics will not burn out for at least 5 seconds. Technical data L x W x H: 40 x 40 x 28 mm Speed: 400 - 15,000rpm Fan bearing: Double ball bearing Connection: 4-pin PWM Cable length: 30 cm Operating voltage: 7 - 14V Starting voltage: 7V Current consumption: 0.33 - 0. 42A (3.96 - 5.04W) Static pressure: 33.9 mm H2O Air flow: 38.39 m3/h Volume max: 49.2 dB(A) MTBF: 70,000h