Using the Fractal North XL Mesh, very quiet, but as with any case with good airflow, using the correct fans is what can make or break for you.
Using Silent Wings 4 140mm HS all around, and the Silent Loop 3 360. Adjusted so I can barely hear the fans, is more than enough cooling for me.
Arctic may show some humming at certain rpm ranges. I like the Thermalright fans better. TL-B12 or 14, or TL-K12 if you need very little RGB. Found them to perform quite well but none of the humming that you are likely to find on the Arctic ones. But if you want to splash and are picky for noise, T30 (only 120mm), Silent Wings 4 or Noctua are safe bets. Noise level is just a part of the history. Sound profile is not something reviews talk about often. EKWB AIOs, for example, dead quiet superb pump, but fans sound a bit rough even at low rpm.