I'm not sure about a long running process, but off the top of my head I could imagine how to monitor a process and adjust its CPU usage for future runs. It wou

I'm not sure about a long running process, but off the top of my head I could imagine how to monitor a process and adjust its CPU usage for future runs. It would very much depend on what kind of hardware you have, though. If the fans are PWM and if they have the RPM line enabled, you could potentially monitor the fan speed and use a utility like cpulimit. Anything else I can think of would require overengineering like building a decibel meter and connecting it over serial or IP.