Quote Originally Posted by Martinm210 View Post
Did a little testing with the voltmeter:

IN
12.0V ->Red
Ground -> Black

After Resistors
After 350 Ohm 11.71V-> Red
After 350 Ohm and other side of 2.2K ohm 11.71V - > Sensor

My first reaction was (The resistors aren't working, but then I realized they don't lower voltage, that lower current) Electronic Noob I am..

I'm wondering if the grey wire with writing on it is really supposed to be power not ground, and I have them backwards?

I also did some voltage testing on the sensor wire that comes out of my pump and it's only registering like 1.3V or so, so there is definately something different here.

Or do motherboards monitor ground pulses instead of power pulses..?
That's weird. I did the same connections and I was able to register the changes but I had to try 1-2 headers before finding the one which can accept the signal. Maybe there are various types of headers or you may have to disable the PWM option because we don't want to control the SF800 voltage. If nothing works, then I think the CrystalFontz option would be easier (just do Sensor / 6000 to get the LPM reading or Sensor / (6000*3.78) for GPM).

If you have a hard time with it, I'll drain the loop partially by clamping the tubing where I'll place the SF800. After this, I'll do my own testing to find out how things work.

Another thing to try would be to invert the ground and sensor wires on the fan connector in case this one is different. Mine has a red edge on the wire but not yours.