be quiet! SILENT WINGS 4 140mm PWM high-speed fan rings at some frequencies

Purchased several high-end 120 and 140 mm fans from be quiet! new Silent Wings 4 series. Imagine my surprise that almost all of them ring unpleasantly at some frequencies. Resonance is clearly audible when the fan changes speed and passes a certain rotation speed, or “freezes” in a certain range according to the current cooling conditions. I found several “ringing” speeds in HW monitoring, setting the speed as a percentage. The reason is definitely not in PW modulation, since: 1) when regulating DC, it also appears (it’s a little more difficult to find, but with transitions with a step of it also appears); 2) if you turn off the power to a fan running at full speed, it will show all the “ringing” peaks while it stops. I installed them as case fans in the 500DX, but they also “ring” outside the case, in the hand (it is clear that in this case they are a little quieter, but still). When working on a radiator, the defect is significantly reduced, but also not completely. MoBo: MSI PRO Z690-A PSU: be quiet! Dark Power Pro 1200W