Closer Examination

If you are even remotely familiar with Noctua's fans, then the color scheme here should be of no surprise. The NF-A12x25 PWM in its current iteration adopts a tan and brown color with a nine-blade impeller on a square frame. But there are plenty of things new here that have not been in Noctua's lineup before, beginning with the liquid-crystal polymer compound used for the impeller. Noctua has trademarked it as "Sterrox", and the use of said material is to help reduce material expansion with temperature and rotational forces. The former is most useful for when the impeller is formed initially, and the latter comes in handy in daily operation. Noctua also claims the material dampens acoustics further, and we will definitely test the fan as a whole for both performance and noise in due time. Note also the channels cut into the leading edge of each blade on the impeller, which Noctua says act as flow-accelerators that help speed up airflow in this region.

The frame in question is Noctua's AAO (Advanced Acoustic Optimization) frame that has been used on their previous fans to good success, with a stepped inlet on all sides accompanying dimpled microstructures. There are also four stator vanes on the back with adjacent vanes perpendicular to each other. Between the Sterrox impeller and AAO frame, Noctua was able to get away with just a ~0.5 mm gap between the extremities of the blades and the inner surface of the frame, which reduced the potential for a pressure drop of the airfield when the fan is up against airflow restriction from, say, a radiator, for example.


All four corners on both sides also get integrated anti-vibration silicone pads with a central closed chamber at the corners. Noctua's logo is printed on to the side of the frame, as are arrows depicting the direction the impeller rotates in, as well as that of the airfield passing through the fan should you need a verification. Noctua is using their excellent SSO2 bearing for this fan (more of this here), which is as expected, but still good to see. The sealed bearing has a brass shell on the outside, but the magnetic field generated by the bearing is still strong enough, as shown by the images above.

Each fan is rated for 0.14 A (1.68 W) on the 12 VDC rail, which corresponds to the peak draw with start-up boost. I noticed a maximum operating current draw of 0.087 A here (~1 W on the 12 V rail), so you should be able to operate a good number of these fans off a single 1 A fan header if start-up boost can be accounted for. Alternatively, you can also get a powered PWM splitter and leave nothing to chance by powering the fans directly through the PSU. Noctua also mentions that the PWM motor used is based on their own custom-designed IC with a zero-RPM mode at 0% PWM duty cycle and lowered PWM switching noise. There were complaints about PWM "ticking" noises from customers of their older PWM fans, especially at lower RPMs, although Noctua says that this is the same IC and people may have been mistaking noise from the three-phase motor in their iPPC PWM fans for PWM switching instead.


The fan has a single power cable for the PWM motor that runs it. As such, we see the four individual wires that make up the cable, and these have black insulation despite the color mismatch, which is much preferred over either a tan or brown sleeving if I say so myself. The sleeving starts just past the edge of the fan's frame, is done in a heat-shrink application, and terminates in a 4-pin fan connector to be plugged into any standard 4-pin PWM header on your motherboard or another similar fan controller. The cable itself is 20 cm long, which is on the shorter side for most full-tower cases that support watercooling, but works great in combination with the supplied 30 cm long extension cable for the best of both worlds.


As seen above, the integrated rubber pads on the corners can easily be removed and replaced with the provided rubber gasket that I recommend using on the side that touches a radiator, should you be using the NF-A12x25 in that application. Doing so would further reduce any vibrations that are passed on to the case through the fan, while also creating a continuous contact layer with the surface of the radiator. If you plan to use it flush against a case, the gasket still maintains compatibility with the soft rubber mounts, which is good to see.