All ventilation fan systems should contain an intake and an exhaust variable, which can be fans or ventilation holes. In an ideal set up, there should be a fan located near the top of the cabinet configured to exhaust out air, and a fan located near the bottom to push in air. Electronics such as receivers and computers within a cabinet will cause air to heat up. Due to natural convection, warmer air which is less dense than colder air will rise on its own. An efficient fan system helps accelerate natural convection by rapidly exhausting warmer air out the top of the cabinet while pushing colder air in at the bottom.