Where to get DDC 3.1 or how to lower DDC speed?

I want to have DDC 3.1, but it seems no longer available.
(I dislike D5 because it is fat, and I knew MCP355 is too noisy for me.)

Options 1: undervolt DDC 3.2. But how?
I am only interested small controllers installed in case: 5.25" bay controller is out of the question.

Options 2: DDC with PWM. But:
1. I am skeptical about their reliability.
2. How to generate the PWM signal by hardware?
Because software fan speed control is often unavailable under linux.

Will this do ? If not the best way to undervolt the 3.2 is using a fan controller. Splicing a 3pin onto the molex, then connect the 3pin to the fan controller.

You can use a simple 25 watt resistor inline. Just find an online LED calculator and plug in your pumps voltage and wattage and a supply voltage (12v) and the calculator will give you a resistor value that will drop line voltage to your target (10 volts for example).
A 25 watt chassis mount resistor is available at mouser.com, and looks like this: