Stumbled across this thread with an issue that is more-or-less in the same area.

I've always used DDC pumps and lately, as I got "older", I liked to decrease their noise by throttling their speed a little. For the last couple of years, I used the regular pumps and some sort of regular power modulation.

Now, for my new build I wanted to get rid of all the extra controllers and got a PWM version of the pump. My issue now is that I don't see how to control its speed. I can see its rpm signal, but no matter how I change the setup in bios, the speed will remain the same.
Is this a common issue? Frankly I haven't used a mainboard's fan control for at least a decade...