"As you can see the Super Tornado comes replete with a rather large list of features, some more important than others. One of the major features of the Super Tornado is Seasonic’s S2FC, or Smart and Silent Fan Control. S2FC is a temperature controlled fan control that does not increase the speed of the fan linearly with the temperature of the power supply, but rather uses a combination of delayed increase in RPM and exponential increase in RPM to produce the desired result. As you can see in this Seasonic diagram, the fan speed increases at a faster rate as the power load on the PSU increases, resulting in a higher heat output and more required cooling. The fan speed is therefore not directly linked to the load upon the power supply, but is still indirectly linked."