DC Fan mini-fan installation

Why "DC Fan" miniature fan mounted on the computer and it can not afford it? A lot of people have experienced, a little longer with the computer it is easy to dropped calls, dropped calls when the "cat" indicator ADSL ( the ACT link lights are flashing lights are not bright), LAN (link light is bright red, ACT lights are not bright) my wireless router flashing indicator is normal, I laptop is wireless Internet access, and if desktop notebook computers are connected together dropped off 10 minutes 1 hour, ranging dropped time.