Dual power supply fan control - thermistor input or software command from the processor

A method for controlling a cooling fan in a complex electronic system, comprising the steps of:

• (a.) turning on said fan when powering up said system;
• (b.) receiving more than one command input;
• and
• (c.) selecting the command input which indicates the highest fan speed to drive the speed of said fan.

A computer system, comprising:

• a user input device, a microprocessor which is operatively connected to detect inputs from said input device, random-access memory which is connected to be read/write accessible by said microprocessor, and an output device operatively connected to receive outputs from said microprocessor;
• and
• a power supply connected to provide power to said microprocessor and said memory, and comprising
• a fan;
• and
• a control circuit connected to receive more than one command input and control said fan accordingly;
• wherein the speed of said fan is varied under at least some circumstances according to thermal environment;
• wherein said control circuit automatically selects the command input which indicates the highest fan speed to drive said fan.