Noctua NF-A14 & 15 Reviewed


Let’s look at the specifications, noting the differences between the 2 models.


A14 – FLX

A14 – ULN

Difference (FLX – ULN)


140x140x25 mm

140x140x25 mm










Blade Geometry

A-Series with Flow Acceleration Channels

A-Series with Flow Acceleration Channels


Frame Technology

AAO (Advanced Acoustic Optimisation)

AAO (Advanced Acoustic Optimisation)


Rotational Speed (+/- 10%)

1200 rpm

800 RPM

400 rpm

Rotational Speed with L.N.A. (+/- 10%)

1050 rpm

650 rpm

400 rpm

Rotational Speed with U.L.N.A. (+/- 10%)

900 rpm



115.5 m³/h

79.8 m³/h

35.7 m³/h

Airflow with L.N.A

101.9 m³/h

66.4 m³/h

35.5 m³/h

Airflow with U.L.N.A

88.7 m³/h


Acoustical Noise

19.2 dB(A)

11.9 dB(A)

7.3 dB(A)

Acoustical Noise with L.N.A

16.4 dB(A)

9.1 dB(A)

7.3 dB(A)

Acoustical Noise with U.L.N.A

13.8 dB(A)


Static Pressure

1.51 mm H2O

0.69 mm H2O

0.82 mm H2O

Static Pressure with L.N.A

1.18 mm H2O

0.42 mm H2O

0.76 mm H2O

Static Pressure with U.L.N.A

0.89 mm H2O


Max. Input Power

0.96 W

0.48 W

0.48 W

Max. Input Current

0.08 A

0.04 A

0.04 A


12 V

12 V



> 150.000 h

> 150.000 h



6 years

6 years


Looking at the specifications above, it’s pretty clear that if you look at the two models on the noise/performance ratio, there is no overlap. We will talk more about what these numbers mean a little later on.


Due to the square frame of the A14, it is able to provide a higher pressure rating for radiators than the older round P14. There is also more recent technology and research behind the newer A14 in terms of aerodynamic optimisations. Noctua has the scientific explanations on their website and we have added references below some of the ‘borrowed’ graphics if you would like to read more.


On the curved side of the blades, there are 3 raised stripes on each blade (A). These are the “Flow Acceleration Channels”, designed to speed up the airflow at the outside of the blades and improve efficiency and noise by reducing “suction side flow separation”. We Googled “Suction Side Airflow” out of curiosity and determination to understand at least some of the hardcore science behind the design here. In a nut-shell, without these Flow Acceleration Channels, the air can ‘leak’ from the tips of the blades and disrupt the vortex, making it inefficient and creating wind noise. By speeding up and directing the airflow as it leaves the outside of the blades, this disruption and noise is reduced. Noctua explain it better on their website with the following graphic.


The Advanced Accoustic Optimisation (AAO) Frame has the anti vibration pads (B), stepped inlet design (C) and inner surface microstructures (D). We saw this same design on the NF-F12 review and it is good to see it consistently implemented on the 140mm product line as well.

The stepped inlet adds turbulence to the intake in order to reduce tonal intake noise, improve flow attachment to the frame and increase suction.

This all translates to less vibration being transferred through the chassis and higher airflow through the inlet because the air hugs the frame. The creation of a boundary layer of air via little dimple microstructures assists with the reduction of the “suction side flow separation” we mentioned earlier. So these technologies all combine to reduce the ‘wind’ noise and at the same time, increase the airflow.

Here are the Noctua diagrams that illustrate the engineering specifics of the frame a little better:




Noctua also implemented the SSO2 bearing (also seen in the NF-F12) where the rear magnet is located closer to the axis to be more stable and precise than the previous SSO. This also apparently increases durability and Noctua back the product with a 6 year warranty which is pretty good for something that spins at 650-1200 rpm. The Mean Time Between Failures is rated at 150,000 hours.

There is other technology implemented here that we saw previously in the NF-F12 such as a brass bearing shell, Smooth Commutation Drive 2 and low power consumption (0.96w for the FLX and 0.48w for the ULN). With the most recent Noctua products sporting the new engineering features, it isn’t surprising to see the older units being discontinued.


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