I just redid my loop and removed the koolance controller I used to use and instead rewired my res fans to run off 2nd cpu fan port on motherboard.
I then wired negative and positive from ddc pump to 12v supply on psu and the rpm/tach cable to the first cpu fan port on motherboard, pin 3..
Im getting 0 reading for fan speed for pump.. I tested rpm/tach cable with a multitester in hz mode and I am getting pulses same as the output of a fan.
What do I need to do to get reading on motherboard from pump, do I need to wire in negative too as ground? or do I need some form of signal inverter?
Basically all I want to do is have the pc shutdown if rpm drops to zero.