For chassis heat also play a cooling effect, "24V DC Cooling Fan" is not enough air flow will cause heat accumulation circulating inside the chassis. Exhaust "24V DC Cooling Fan" surrounding hinder relatively much less, then the air pressure is much larger than the amount of the claim. At the same time, the heat inside the chassis can be more quickly discharged outside of the chassis. In addition, most of the chassis side and a top layer of thermal windows only punch mesh design, so the use of wind capacity is characterized by "24V DC Cooling Fan" is a good choice.