For Fans with integrated PWM controllers Good practice is to install a single series resistor (50-100Ohm) to limit the current in case of accidental short circuit or failure of the fan. No additional hardware is necessary, and if you can tollerate that risk it will be fine for reasonable <1M long GPIO cables without a series resistor.
Note that some people still choose to install a discrete driver in front of the GPIO, this only needs to be a logic level device or buffer.
The manufacturer of your fan provides a global "PWM" Specification for their products. They call it a "white paper" which is simply that they do not guarantee anything in this document, but it is as good as it gets. If you can find it they reference the formal Intel Spec : “4-Wire Pulse Width Modulation (PWM) Controlled Fans”, Intel
Corporation September 2005, revision 1.3
Page 6 of the whitesheet we see
- Maximum voltage for logic low: VIL=0,8V
- Absolute maximum current sourced: Imax=5mA (short circuit current)
- Absolute maximum voltage level: VMax=5,25V (open circuit voltage)
- External pull-up is not necessary as the signal is pulled up to 3,3V/5V inside the fan.
They even provide a handy reference
In this case, this is a simple logic level PWM signal, with no unusual requirements and without the gate capacitance issue requiring the series resistor. They also have an onboard pullup so no floating pin concerns. Check check!
Note that you still have to provide 5/12/24V to the fan. See Below.
Power supply is provided on different pin from PWM
B - PWM
G - Feedback
Y - V+
B - GND
The built in PWM means that the circuit in your question is integrated. However, the details of this are hidden from you, so we must rely on the spec and not guess what is the internal driver
Page 6 of the white sheet