Shown on this slide, 12 V fan motor drivers are found in desktop computers and all-in-one computers. They sit on top of the processor and they also ventilate the case. The all-in-one computer designers are taking what once used to be two or three fans and reducing them to one. The tight spaces require low power yet high current output. They also want the ability to change the speed of the fan based on a thermal input, usually from a thermistor. Desktop PCs, which usually sit on the floor beneath a desk, do not value quiet operation as important as cost. For the all-in-one PCs, which actually do sit on the desk, the PWM switched method is a good trade off for cost vs. quietness.