I also bought two Noctua R8 case fans because I identified that the buzzing was coming from one of the Xilence fans!
Xilence fans are usually not that bad, and the expensive Noctuas would look like an overkill (other cheaper fans may work well, like AC F8 PWM or Nexus Basic).
Here is what profile I have the fans on
As already said by xan_user, the EZ mode isn't the best option for operating a quiet rig.
Broadly speaking, your fans look like too much fast spinning, so, more probably that not, you should set up more sensible fan curves, as your hardware shouldn't require more than 6-800rpm.