Results: Static pressure through a nylon filter
Longer life in exchange for more noise? These are also some of the agenda items we’ll cover in our comparison of the Arctic P14 CO fan with the fluid bearing variant. These are actually the main points. In any case, the ball bearings in the more expensive variant of these fans also have specific features that can be easily observed and distinguished even in normal, “home” use.
Results: Static pressure through a nylon filter
Note: “Higher is better” (the result of static pressure in the charts) is only valid for comparing fans of the same formats. We have discussed what the quantity “static pressure” means and how to understand it in this article.
Why is there a missing value sometimes? There may be more reasons. Usually it is because the fan could not be adjusted to the target noise level. Some have a higher minimum speed (or the speed is low, but the motor is too noisy) or it is a slower fan that will not reach the higher decibels. But the results in the graphs are also missing if the impeller is brushing against the nylon filter mesh. In that case, we evaluate this combination as incompatible. And zero in the graphs is naturally also in situations where we measure 0.00. This is a common occurrence at extremely low speeds with obstructions or within vibration measurements.
- Contents
- Arctic P14 PWM PST CO 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)
- Measurement of static pressure…
- … and of 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
Expected results, but still an interesting showcase of the effect of only changing the bearings.
So, the “hum” is still here all the same, despite some claims that the CO version fixes it. ThermalLeft has documented sound differences between revisions too (https://www.youtube.com/watch?v=nt8Ao4GDmzY), but even Arctic themselves doesn’t think revisions will have such an effect. I am starting to think it’s possibly a batch “issue” that may have introduced different properties to the rotor material.
I guess those claims of the CO rumbling less will never come from an official source (from Arctic)? They don’t seem to list among the changes across the revisions the modifications that address this. And personally, I don’t even see the technical reason behind the CO variant or the higher P14 revision (2 vs. 4) being quieter on lower frequencies. The impeller seems to have the same parameters in terms of geometry or material used. Nevertheless, there can certainly be a situation where different noise levels are measured across different fans. But it may not be due to different revisions, and perhaps it may be possible to observe this across different fan pieces of the same revision due to different manufacturing tolerances (which are high in the low-end after all)?
An analysis that tracks the tonal peaks of multiple pieces from the same revisions on each side would shed more light on this. From our experience, we note that the shape of the spectrograms of multiple pieces of the P14 PWM PST rev. 4 compared to P14 PWM PST CO rev. 3 in the low frequency band is identical at the same speed. The small differences in the spectrograms that you see in the tests are mainly just due to the fact that in modes normalized by the same noise levels, the speeds of the two variants (P14 and P14 CO fans) are slightly different. For the CO, the speeds are always set a little lower due to the noisier bearings.
Perhaps what is known as “resonance” is something else that’s not the frequency spike at ~100 Hz. Namely, the sudden increase in noise at specific RPM ranges. Or, perhaps the two issues are lumped together when people talk about it, when in fact the two (sound profile with pronounced low frequency peak, and some RPM ranges being suddenly louder) are different issues (that perhaps are related).
I am sure you would have noticed and mentioned it though, when you’re testing the fans and adjusting the fan speeds again and again.