a simple hardware fact

[akash shrestha]

Why does a CPU's, PSU fan specially most of the desktops, makes a loud humming noise at the start up and then it becomes normal after some minutes?

Edited January 14, 2012 by akash shrestha

[insane_alien]

changes in the fans speed means there are changes in torque being supplied by the motor. This can create noise which is caused by additional vibrations. Once the computer has reached a thermal equilibrium (the amount of heat being removed has steadied) then the fan has no need to speed up and the forces will be almost constant which will limit the vibrations and hence noise.

[akash shrestha]

Thank You.