Any other speed controller for 4-pin PWM fans on the market?

Yes, you can provide power AND control the speed of a 4-pin fan using Voltage Control Mode that is used for control of 3-pin fans, as most third-party fan controllers do. You probably do NOT even need an adapter. You see, the mechanical and electrical layout of pins for fan connectors are set up for this backwards compatibility. Normally you CAN fit the female 4-pin connector from your fan onto the male 3-pin header of a fan power source, and it will work fine. What is "missing" in this connection is that the fan never receives a PWM signal from the 4th pin that is not used, BUT the power supplied on Pin #2 is not a fixed +12 VDC that a proper 4-pin header would provide. It is a VARYING +VDC, so that controls fan speed. The only PROBLEM might be a poor mechanical design of the controller's output connector. A mobo 3-pin male header is just 3 pins sticking up with a guide "tongue" next to them, so a wider 4-pin male connector fits on just fine. Some output connectors on fan controllers MAY have shrounds around the pins that prevent fitting the wider 4-pin male, OR they might be closely spaced together to interfere. So you MIGHT have to make some minor adjustment to the controller's output connectors. Bear that in mind in choosing a controller.

HOWEVER, the Noctua site for that iPPC fan does have a caution in one of its FAQ answers, as follows.


Can industrialPPC fans be used with fan controllers and resistor cables (Low-Noise Adaptors)?

Noctua recommends not to use industrialPPC fans with common PC fan controllers, resistor cables (Low-Noise Adaptors) or other devices such as potentiometers that work by applying (variable) resistance rather than actually generating different voltages such as a laboratory power supply does. Due to the higher internal resistance of the industrialPPC fans’ three phase motor, applying additional resistance will cause the fans not to start (e.g. with Low-Noise Adaptors) or to have high starting speeds (e.g. with most common PC fan controllers). Please note that the industrialPPC fans feature starting voltages between 5.5V and 6V and can be run at these voltages on devices such as laboratory power supplies or mainboard fan controllers which actually generate lower voltages rather than applying resistance. Noctua thus recommends to use either PWM or voltage based mainboard fan control or laboratory/industrial power supplies for controlling the speed of industrialPPC fans.


So, the iPPC design of fan motors are 3-phase (not 2-phase like common fans) for greater power and efficiency. Among other things, this means its internal resistance is higher than common fans. At the same time, it actually consumes more power (and hence uses more current) than a common fan in order to deliver the much higher air flow at its max speed. MANY common fan controllers use a simple method of varying the voltage they supply to their fan. They simply add an extra (adjustable) resistance in series with the fan, thus reducing the voltage the fan gets. The amount of voltage the controller drops with its own resistance depends on the current flowing through it and the fan. If the fan draws more current than a "normal" fan at some reduced-speed setting (say, 60% on a knob dial), the actual voltage being supplied to the iPPC fan is LOWER that a "normal" fan would get. So Noctua warns that using such a controller CAN produce a stalled fan because the fan is running slower than you might expect according to the marking on the control knob. This is not a big problem at very high settings, but an iPPC fan could stall (or, fail to start up) if its control knob is set too low.

You certainly can learn what knob settings to make using a third-party speed controller module for your iPPC fan. You just need to be aware of this factor and adjust accordingly.