System 2 original fan speed is proportional to temperature rise, relieving the system designer of control issues. As equipment warms fans begin to turn at about 1/3 of full speed increasing to 2/3 of full speed if temperature rises further. When the system is turned off fan speed slows as temperature falls shutting off completely just above room temperature. Speed limitation and the use of multiple fans ensure effective cooling with very little noise. The original System 2 has 2 fans and drives electronics on 1/8-inch black mounting plate and is usually mounted on the back of cabinet to exhaust hot air.