Logisys Glacier Dual LED Fan 500W Power Supply
 

Review Quote: "The silver control knob on the back of the Logisys Glacier power supply controls
the speed of the two fans... Unfortunately the control knob was not very reliable; it only worked
for about an hour. During that hour, I was able to adjust the speed of the fans (and the brightness
of the fan LEDs). Shortly thereafter, I needed to leave the room so I turned the fans down to the
middle speed. When I came back, the fans were off..."

http://www.bigbruin.com/reviews/logisysglacier/