Excuse my lack of knowledge on PWM and fans, but can a fan configured with 4 wires (power, ground, tach. signal, and PWM input) be run off of a DC power supply without using the PWM to control its speed? As in, not using the PWM lead and just hooking up power/ground and controlling fan speed by adjusting voltage? Or is it required that the PWM be used if you wanted to be able to adjust the fan speed. This is the fan I was looking at: http://search.digikey.com/us/en/products/3122FT-D4W-B56-E50/P14778-ND/2647852 [Broken] Don't have much of an electrical background so I was hoping someone with more knowledge could help me out.