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.
Measurement of static pressure…
Finally, it is time to move further down the tunnel a bit. Just behind the fan is a static pressure sensing probe. Its position has been chosen with maximum measurement efficiency in mind. In other words, the sensors are placed at the points of highest pressure (although this is virtually the same everywhere in the unconstrained part of the tunnel).
The Fieldpiece ASP2, which is connected to the Fieldpiece SDMN5 manometer, is used to measure the static pressure in the tunnel. The latter also allows measurements in millimetres of water column, but we measure in millibars. This is a more finely resolved base unit for this meter. And only from there we convert the measured values into mm H2O to allow easy comparison with what the manufacturers state.
While we wrote when measuring noise levels that our results could not be compared with the parameters, that is no longer the case here. As long as the fan manufacturers do not embellish the parameters, they should quote approximately the same pressure values as our tests show. The most significant deviations can only arise at the level of varying accuracy of the measuring instruments, but these are negligible percentages.
The greater the difference between the manufacturer’s claimed values and ours, the less the specifications correspond to reality. If the claimed values are significantly higher, it is certainly an intention to artificially give an advantage to the fans on the market. However, if the manufacturer quotes a lower pressure value than we do, it points to something else. Namely, a weaker tightness of the measuring environment. The less tight the tunnel is, the lower the pressure you naturally measure. This is one of the things we tuned for an extremely long time, but in the end we ironed out all the weak spots. Whether it’s the passage for the probe itself, the flanges around the anemometer, even the anemometer frame itself, which is made up of two parts, needed to be sealed in the middle. Finally, the flap at the tunnel outlet must also be perfectly tight. That’s because static pressure has to be measured in zero airflow.
But there is one thing that often lowers the pressure of the fans a bit. And that’s protruding anti-vibration pads in the corners or otherwise protruding corners. In other words, when the fan doesn’t fit perfectly to the mounting frame at the inlet, and there are small gaps around the perimeter, that also affects what you measure. But we have not gone into this because it is already a quality feature of the fan. In the same way, it will “stand out” and perform a bit weaker than it has the potential to do with better workmanship, even after application by the end user.
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.
Good day,
can the testers please answer this?
So P12 Max, P14 Max have both the better FDB, and only the CO versions have the ball bearing?
For both black and white version of the P12/14 Max?
Thanks
When the Max debuted (black color), it had a DBB. Later when the white version came, it had an FDB. Then they switched both models to FDB. The only Arctic fans that have a DBB nowadays are the “CO“ (continuous operation) and all server-grade fans (starting with the letter “S”)
DBB is optimal in harsh environments (higher temperature) and for continuous operation.
(I hope you don’t mind that I’m not a reviewer) 😉
It’s exactly as Bufo says. The P12 Max fan in its second revision already uses FDB. Ball bearings were only present in the first revision (P12 Max rev. 1). The unwanted whining noise that many users complained about no longer applies to the P12 Max rev. 2. Proof of this can also be seen in the sound spectrogram, where there are no significant tonal peaks at high frequencies. 🙂