How can is overheating of computers solved, describe the process thermistors through thermostats?

Computers can often overheat, to reduce this, computer usually have a fan; when the temperature of the computer rises the fan switches on and cool it back down, (in this series the thermistor is connected in series with a cooling fan) Under cool conditions the resistance of the thermistors is high so it takes a lot of energy for the current to pass through it, therefore the potential difference across the thermistor is high and as the potential difference is shared between components in series, the fan has a small potential difference, which means the fan operates at a very low speed While if the computer gets hot the resistance of the thermistor falls and less energy is need for the current to pass through the thermistor so the potential difference across the thermistor is very low so more electrical energy is available for the fan; making the potential difference across the fan very high so the fan powers up to high speed; cooling the computer back down.