PWM a 3-pin PC fan with an Arduino - Bald Engineer

Use a PNP transistor to PWM a 3-pin PC Fan with an Arduino. Because of how PNP transistors work, you'll need to use a NPN driver as well.

Benchmarking Arduino's digitalWrite() with a Logic Analyzer - Bald Engineer

How to implement PWM fan driver using configurable chips - Planet Analog

Automatic 4-channel pwm PC fan controller.

PWM a 3-pin PC fan with an Arduino - Bald Engineer

Arduino Software PWM with millis() - Bald Engineer

Arduino PWM pc fan control

So you want PWM control of your 3-pin fan?, Page 5

Control PWM Fans with an Arduino

PWM a 3-pin PC fan with an Arduino - Bald Engineer

This CPU fan speed reduction cable is made of high-quality insulating material PVC, which can be used for a long time, so that you can no longer bear

3-Pin Fan Deceleration Line DGZZI Male-to-Female CPU Fan PWM Cable,Temperature Control Descending Speed line for Computer PC Case Fan RPM Connector

PWM a 3-pin PC fan with an Arduino - Bald Engineer

3 pin PC fan - Project Guidance - Arduino Forum

Arduino PWM Fan Controller – Microcontroller Based Projects