BeQuiet! Pure Wings 2 (BL039): It wouldn’t do without the grooves

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 rotor 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.