I bought a Sunon 5020 12 V blower/radial fan for my CR-10S and it makes a really nasty high pitched noise at full power. I read that PWM can cause this but not at full power, I have tried all marlin (running Marlin 18.104.22.168) options to change PWM frequency with no effect, also tried connecting it straight to 12 V with two separate power supplies and the noise was still there, tried putting a 470 μF cap across the pins to see if that would help but it didn't. I also took it off from the petsfang (which is a fan duct designed for Creality 3D printers) to see if that was causing it but no. So, I have eliminated firmware, power supply and the fan duct and I am sure it is the fan itself causing this. You can find video of the noise here. How do I eliminate the noise?
(I have an MKS GEN L motherboard with TMC2130 stepper drivers, an E3D Lite6 hotend with a Noctua 4020 cooling fan)