Fan is the most populer part in Electric enginering, they
have job to colling down a part witch have hot temp and product hot temperature
from there perform. Personal Computer (PC) is the example one of electronic
part, they have many part of producting hot temperature until 100 degree, its
enaugh to burn your PC if you don't have this agent to colling your PC.
Usally
in PC fan can be applaied at CPU, Case Mount, Graphic Card, Chipset, and
another place that need it, and i want to present you about how can control CPU
fan Speed manually with simplfy hardware, you can buy a Fan Controller on the
market, but you can control your Fan like you want and you must have much money
to bough this, but if you want make it you can save much money because you can
make it with simplify electronic basic component, even that you can make it
from 2 resistor or potentiometer if yo want change the variable of Fan speed,
but i don't recomend that because you don't get a good electrical circuit.