Comment by kllrnohj

The fan blades deform & vibrate under rotation & airflow. Controlling that deformation is the point of the use of materials like Noctua's Sterrox LCP or other flglass-fiber reinforced LCP materials in other premium fans. So lower clearance isn't just a matter of manufacturing tolerance

Noctua talks about it on this page: https://www.noctua.at/en/expertise/tech/sterroxr-liquid-crys...