Patent ID: 7501717

Claim:
A method for identifying whether a first fan or a second fan is connected to a receptacle of a computer system, the receptacle comprising a power pin, a detection pin and a speed control pin, the speed of the first fan being controlled through the speed control pin, and the speed of the second fan being controlled through the power pin, the method comprising the steps of: providing a drive voltage continuously to the power pin of the receptacle according to a power control signal and/or a forced control signal; inputting a speed control signal with a first duty cycle to the speed control pin of the receptacle; obtaining a first speed from the detection pin of the receptacle; changing the speed control signal from the first duty cycle to a second duty cycle; obtaining a second speed from the detection pin of the receptacle; and identifying whether the first fan or the second fan is connected to the receptacle by comparing a differentiation percentage of the first speed and the second speed to a threshold.