I love Noctua, but a totally fanless system would be a more interesting test.
As a matter of fact, Noctua has a compatibility guide where they list the expected performance w/ and w/o a fan[1].
Of course they do. Noctua is an excellent company. Hard to imagine how they might improve. And some credit to PC builders is deserved as well; they've supported this company and its products and paid the requisite price for years, despite a literal horde of cheaper competition.
I appreciate how little regard they have for the RGB blinkenlights crowd.
With the right case (Fractal Define) and 3 case fans dialed down it's possible to make the system basically silent. Then replace HDDs with SSDs and a passively cooled gpu.
Might work for extremely energy efficient systems, though.
It be perfect for my DIY home NAS build.