Because OP uses a (mid-sized, but large by most standards) AIO with two Noctua redux PF-12 1700 PWM's.

So... your recommendation is the article.

Did you read my comment? I said buy a large AIO and then don’t do the rest of the article and then it actually is quiet with no effort. Large.

Oh, c'mon, you weren't this specific. And I was. A 240mm rad is large by normal standards. Sure, a 360mm one is larger, but also usually not needed and you are likely to run into clearance issues.

I mounted it outside the case. Lots of cases have little cutouts to facilitate this. The fact you are sucking hot air into the radiator is probably not helping you.

360mm isn't needed, unless you want it to be quiet...