Mounting and vibration measurement
Blade length is always the “topic”, but will be more common with 140mm fans than smaller variants. Some bet on long blades for preference of selected features, the other manufacturer on short ones. And such (short) and overall more robust blades are also used by the 140mm Aorus fan. From certain points of view this is quite a big advantage, but for which something had to be sacrificed. It’s a quid pro quo.
Mounting and vibration measurement
Naturally, each tested fan must first be properly mounted. With all that we want to measure, and with the kind of precision that is required for relevant measurements, even the smallest details matter. The whole mounting system is quite complex and we are happy to have fine-tuned it to maximum satisfaction. Even if it meant hundreds of hours of tinkering. What’s so complicated about it? There’s more.
The fans are installed to the multi-purpose bracket. The substrate is a 2 mm thick metal plate to which the fan is attached, or the fan is attached together with an obstacle (e.g. a filter, hexagonal grille or liquid cooler radiator).
For correct and always equal pressure, the fans are always tightened with the same force with a torque screwdriver. If this were not the case, joints and clearances in the assembly could arise, in short, uneven conditions with undesirable distortion. For example, also for vibration measurement. On top of the fan mount there is also a bracket for the three-axis vibrometer sensor. The latter is magnetically attached via a steel insert, on which the sensor exerts a force of one kilogram and, thanks to the stop, is also always in the same place and in the same contact with the rest of the structure. These are the basics in terms of repeatability of measurements.
In order to capture the intensity at the highest possible resolution, the tray of the holder cannot be too heavy and at the same time it must be strong enough not to twist. This would again cause various distortions. Therefore, we used a hard (H19) aluminium (AL99.5) plate for the construction of the holder, whose weight is just enough so that free movement is not significantly restricted.
To achieve the finest possible resolution for vibration measurement, soft rubber inserts are provided in the mounting holes through which the bracket is installed to the tunnel. And just behind these inserts are silent blocks with a very low hardness of 30 Shore. These are also used so that the vibrations of the fans don’t spread to the tunnel skeleton. If this were to happen, then for fans with more intense vibrations, this secondary noise component, which is not related to the aerodynamic sound of the fan, would also be reflected in the noise measurement results.
This is where it is good to have ideal conditions, even though they are unattainable in practice, because fan vibrations will always be transmitted to the case skeleton to some degree. But each cabinet will react differently to them, or rather the final noise level will depend on a number of factors, starting with the materials used. Therefore, it is a good idea to filter out this extra noise component in tests and in practice take into account the measured vibration intensities. The higher these vibrations are, the higher the noise addition has to be taken into account.
The silent blocks are naturally formatted to offset the bracket a bit from the rest of the tunnel, otherwise they wouldn’t make sense. This creates a gap that is sealed across the entire surface with a soft foam seal with closed cell structure (i.e., it’s airtight).
To properly center the fan rotor in relation to the other elements, the bracket includes a protruding frame that follows the inner contour of the seal. And to make matters even more complicated, the frame with the tested fan is pressed against this seal by a small force of compression springs, which in turn is set with the highest possible resolution for vibration measurement in mind and at the same time so that sufficient pressure is generated to maintain a flawless seal.
Vibration is measured with a Landtek VM-6380 vibration meter. It records the vibration speed (in mm) per second in all axes (X, Y, Z). For quick orientation, we calculate a 3D vector from the measured values and graph the “total” vibration intensity. But you can also find your results if you are only interested in a specific axis.
The most complicated part of the tunnel is behind us, and we’ll move on in the next chapter. But we will still stay at the beginning of the tunnel, we will just turn to the peripheries on the sides.
- Contents
- Gigabyte Aorus 140 ARGB in detail
- 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 by 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
Nice to see the 140mm fan reviews rolling!
Also, would it be possible to publish noise samples for your fan/cooler reviews? Preferably for all scenarios where you perform frequency analysis?
And they will continue to come, tests of 140 mm fans. But we probably won’t exaggerate it, so that they stay in a relevant ratio (according to the interest in whichever format in general) to 120 mm models.
Which noise samples do you mean? From spectrographs? Do you want that data for your own purposes, for your own analysis? If so, we can send you the noise levels at all frequencies in all tested scenarios almost immediately (e.g. by e-mail). We can certainly post them on the web somewhere, but it will take more time, as we will need to create a section for this somewhere. Making it make sense on the web will be more time-consuming and at the moment we are quite overloaded and it is hard to find space for extra activities. :/
Always looking forward to your fan reviews regardless of size!
For noise samples, I mean audio files so I can listen to them to make a subjective judgement. In reviews you often mention the differences in frequencies between obstacles/fan models etc. With audio files to listen to, it will be much more easy to understand the difference.
Maybe you can consider compiling the audio files for each fan and upload to YouTube as a video, for example, which perhaps take relatively little effort, though I am not sure if the audio quality is satisfactory. Anyway, it is only a suggestion so please decide on whether you think it is worth the effort or not.
I understand now, and I am also sorry that I am now likely to disappoint you.
Sound recordings are something I boycott against and the goal is to get more and more people to learn to read spectrograms. Sure, it’s more complicated, but we plan to publish materials to facilitate reading these charts. We will select a few fans that have the biggest differences in the frequency characteristic of the sound, make a sound recording of them, and put a spectrogram against it. On it we then explain which component of the sound represents what in the spectral analysis.
You know, I’m willing to sacrifice all my time for these things, but I have to see some meaning behind the results. And sound recordings don’t make sense to me because they can be extremely misleading. While the user thinks he’s hearing the fan, the sound system with the speaker on top is laughing at how they have been perfectly fooled. It is certainly not necessary to elaborate that the same recording sounds different on each speaker (it is determined by the frequency characteristics of the sound equipment of the end user), and this also with regard to the volume that the person sets. To judge something on the basis of the sound recording is therefore very inaccurate and misleading. I would probably suffer a lot when making them with my high demands on the relevance of things and at the same time it would reduce the relevance of spectrogram, which everyone sees the same way.
I believe that after this message you will not give up on our tests and sooner or later you will surely find out (also with the help of various auxiliary materials, which we plan to publish on this topic), that you understand everything perfectly also with the help of spectrograms. 🙂
Not disappointed at all, very satisfied with your answer. Looking forward to the articles explaining spectrograms, I’ll admit I never really understood how to interpret them.