Noctua NF-A14 PWM: Relevant even after a decade

Everything changes with obstacles

There aren’t many 140mm fans that are more popular than the NF-A14 (PWM). This Noctua model has maintained that for a long time, for over a decade. In the meantime, naturally, a host of newer competing solutions have come along, and the question is how Noctua’s still-flagship 140mm fan will hold up against them in the present day. By analyzing the NF-A14, we’ll also shorten a bit the interminable wait for its successor.

Everything changes with obstacles

So far, we have described how static pressure and airflow measurements are made under conditions where the fan has no obstacles in its path. In practice, however, fans do not usually blow into an empty space, but have a filter, grille or radiator in front of or behind them, the fins of which need to be pushed through as efficiently as possible.

We will also measure both airflow and pressure through practical obstacles for the reasons stated above. These include two types of filters that are usually used in PC cases. One fine – nylon and the other plastic with a thinner mesh. One other obstacle is the hexagonal grille perforated at 50%, on which the vast majority of fans – intake and exhaust – are installed. In some cases, we measure the effect of the obstacles on the results at positions (behind or in front of the impeller) that are used in practice. All obstacles are both pushed through to detect pressure drops, but also pulled through, which in turn speaks to the impact on airflow.

We use two radiators that differ in thickness and fin density. The EK CoolStream SE120/140 is 28 mm thick and the FPI is 22, the Alphacool NexXxoS XT45 v2 is thicker (45 mm) but with less FPI. CoolStream’s fin disposition is also similar in parameters to AIOs. The results on the NexXxoS will again be attractive for those who build their own water cooling loops, where the fans should work well even at low speeds – hence the lower fin density.

These obstacles and especially the radiators, but also the grilles, increase the mechanical resistance in front of the fan, resulting in higher noise levels. However, we will still tune the fan speeds to the specified noise levels of 31 to 45 dBA. Naturally, the speeds will always be lower than when testing without obstructions, but we will maintain the noise levels for clarity. The different noise levels with and without obstacles will only be at maximum power. In this mode it will also be nice to see how the fan design works with the obstacle and in which case the noise level increases more and in which less.

• Contents
• Noctua NF-A14 PWM in detail
• Overview of manufacturer specifications
• Basis of the methodology, the wind tunnel
• Mounting and vibration measurement
• Initial warm-up and speed recording
• Base 6 equal noise levels…
• ... and sound color (frequency characteristic)
• Static pressure measurement…
• … and airflow
• Everything changes with obstacles
• How we measure power draw and motor power
• Measuring the intensity (and power draw) of lighting
• Results: Speed
• Results: Airlow w/o obstacles
• Results: Airflow through a nylon filter
• Results: Airflow through a plastic filter
• Results: Airflow through a hexagonal grille
• Results: Airflow through a thinner radiator
• Results: Airflow through a thicker radiator
• Results: Static pressure w/o obstacles
• Results: Static pressure through a nylon filter
• Results: Static pressure through a plastic filter
• Results: Static pressure through a hexagonal grille
• Results: Static pressure through a thinner radiator
• Results: Static pressure through a thicker radiator
• Results: Static pressure, efficiency depending on orientation
• Reality vs. specifications
• Results: Frequency response of sound w/o obstacles
• Results: Frequency response of sound with a dust filter
• Results: Frequency response of sound with a hexagonal grille
• Results: Frequency response of sound with a radiator
• Results: Vibration, in total (3D vector length)
• Results: Vibration, X-axis
• Results: Vibration, Y-axis
• Results: Vibration, Z-axis
• Results: Power draw (and motor power)
• Results: Cooling performance per watt, airflow
• Results: Cooling performance per watt, static pressure
• Airflow per euro
• Static pressure per euro
• Results: Lighting – LED luminance and power draw
• Results: LED to motor power draw ratio
• Evaluation