Isn't the problem with Noctua (and similar "silent" fans) that they don't offer the same airflow throughput as their noise making bretheren ?
So sometimes its not as easy as "just use Noctua" ?
I have RMA'd many fans through them and the experience is quick and painless every time.
They have a range of fan speeds going up to very high speeds.
Many people doing modifications will substitute a lower airflow fan for even more noise reduction, which might be why you’re thinking they flow less. That’s a function of fan choice, though.
Noctua fans perform very well on a noise-adjusted basis.
But I don't think that's an issue for computer cooling unless you're talking about extreme circumstances.
They have better airflow design and sound dampening/isolating screw mounts.
I think the idea about reduced airflow might be backwards - most systems use PWM to spin the fans based on CPU or system temperature. This means the systems get the airflow they need.
Also, they make larger heatsinks + fans for certain systems that allow the same airflow using a larger, slower spinning fan. which means less sound.
that said, there are some noctua fans that can spin faster than others.
If you're looking for 40mm or 80mm you're better off with sunon maglev or similar