Thanks to psychoacoustic optimizations like the Vortex-Control Notches, the new SCD drive system and Noctua's premium-grade SSO-Bearing, the NF-B9 achieves exceptional quietness and long-term stability. Due to the advanced design measures like the bevelled blade tips, the NF-B9 is surprisingly quiet despite its outstanding airflow and pressure performance. The psychoacoustic optimisations like the Vortex-Control Noctches make the NF-B9's noise pattern more pleasant to the human ear. The new SC drive system reduces torque variations and thereby ensures improved running smoothness particularly at lower speeds. Noctua's well proven SSO-Bearing technology gaurantees supremely quiet operation and exceptional long-term stability.