Question Corsair iCUE H150i ELITE CAPELLIX XT humming noise

[Firebolt1]

Hello!

Yesterday I built a new PC and one thing kind of caught me off-guard - the AIO cooler fans seem to be creating this very awkward non-stop humming noise (pattern is like a slow rap beat and it sounds like a very toned down siren) on higher RPM. I made sure to tighten every single screw as best I could but it doesn’t help at all

The AIO is mounted on top of the case. Under higher load, when I turn off only the fan in the middle, the noise stops. If I turn off only the fan closer to the front of the case, the noise stops. If I turn off only the fan closer to the back of the case, the humming continues.

Does anybody have any idea what could be causing this? I thought it was a faulty fan when I found out the noise stops when I turn off the fan in the middle but then I found out it stops also when the other one is off. I am honestly completely lost here. Had a Corsair AIO previously and never had any issue like this,

 

[Aeacus]

Open up your PC case and put your ear to it, to find out from where it exactly comes from.

But other than that, it could be airflow noise. This explains why stopping only single fan (front or middle) makes the sound go away and also why it only appears on high RPM (more airflow).