Your fans is not the problem. Linear regulators works well with 3 pin fans. Back in the day, I created well designed regulator on a experimental PCB with many components for 3 pin fans to quieten down computer.
I investigated the fan controller you linked recently as I'm still looking for *true* manually adjustable PWM signal controller on a bracket and turns out there is no extra components required to generate PWM signal. These "fets" are actually linear voltage regulators dialed by the potimeter. This *does not* work with PWM fans especially greater than 1A fans as they sped up to full speed no matter what.
Currently Noctua only have this one but it is expensive at 40 to 50 a pop. Chinese trinkets on the market does have real PWM adjustable but this is bare board, not even in a box, temperature (I have two and I used it without sensors to evaluate my collection of PWM fans for specific purpose (air pump with pressure and hose, to inflate plastic bags) and push buttons (complicated way to adjust) not knob not even assembled to a bracket. Disadvantage is it's microcontroller, disadvantage two, no selectable frequency like 25KHz or 16KHz, third disadvantage is no switch to invert a PWM signal.
People are making 1-100% PWM controllers set by a pot using two 555 timers and LM113, with kick start feature added on, negative thing is nobody had designed boards singles and multiples to sell bare boards so anyone can solder the parts on. Also designed to use project boxes. This also allows you to change frequency as well by swapping a capacitor and add a simple circuit to invert PWM signal.
The attributes of server fans are very particular about PWM signal requires this.
I would do that too as I plan to make one. They are on overlockers forums. I'll link these direct to there after work, I'm on work computer which does not have the links.
As promised, here's the link to schematic to make the true PWM signal output and it is heavily tested and researched as bing needed to run server fans properly. the one 1-100% works best, and few notes on how to add features and change either 25KHz or 16KHz is one capacitor change.
https://www.overclockers.com/forums/showthrea … 318#post6473318
Great Northern aka Canada.