Katimon was originally made to keep the noise of an Asus EAH4870 card to low levels without risking high temperatures. In other words, it was made to auto-adjust the fan speed depending on the card temperature.

The automatic fan control uses two predefined temperature limits, a lower limit and an upper limit. They are both defined in the settings dialog. It also uses two predefined fan speed limits (again a lower and an upper limit). When the temperature is lower than the lower limit, the fan speed becomes the lower defined fan speed. When the temperature exceeds the upper limit, the fan speed becomes the maximum one. The fan speed changes proportionally to the temperature.

The fan speed increases in steps of 20 percentage units and decreases in steps of 10 percentage units. This ensures that the fan speed will increase fast enough when the temperature raises. The actual fan speed can differ up to 10 percentage units from the target fan speed. This avoids the ping-pong effect of continuously increasing and decreasing the fan speed which has really annoying noise results (really!).

The fan control logic seems to be quite effective and very stable. GPU temperature is kept in the predefined limits (as long as the fan can cope with the temperature). The noise level is kept to a minimum without risking graphics card damage.