.. sorry to bother you so much, but - in spite of not being an electronics noob - never heard of something like that. the cheap radials are available for 24 volts anyway, so would be only needed for 12 v (axial, available in quality) but is interesting. do you mean like in the attached drawing (gnd is routed straight through the module and mustn´t connect 2 different ground potentials??!!, so wether connect the blue gnd to the fan plug OR connect black to "pwm contr. gnd")? and if so (or similar) - what you mean by "pwm controlled ground" and where would it to be found (onboard - rev. 1.1.3)?