Case Fan Noctua NF-A14X25r G2 PWM SX2-PP 140mm 2xFans

Noctua NF-A14X25r G2 PWM SX2-PP

The NF-A14x25r G2 PWM Sx2-PP is a set of two 140mm NF-A14x25r G2 PWM fans with a round frame, designed for use with heatsinks like the NH-D15(S) or NH-U14S.

When both fans operate in a push-pull configuration at nearly the same constant speed,

their acoustic interaction can lead to unwanted harmonic effects such as intermittent vibrations or periodic humming due to interference, which can be perceived as beat frequencies.

To prevent such phenomena, the two NF-A14x25r G2 PWM fans included in the Sx2-PP set are slightly offset in speed (+/- ~25rpm).

This fine-tuning is made possible by the fans' new etaPERF motor and its NE-FD6 IC Driver, which achieve exceptionally precise speed control,

and thanks to its SupraTorque feature, it can leverage additional torque margin to maintain the desired and precise speed even when operating against significant airflow resistance, such as on heatsinks.

With one fan running at a slightly slower pace of ~25 RPM (PPA) and the other at ~25 RPM faster (PPB), overall cooling performance can be maintained while effectively preventing intermittent vibrations or periodic humming.

Since the perception of beat frequencies can vary according to acoustic preferences,

users can easily further optimize acoustics by slightly slowing down the PPA fan using PWM control or a Low-Noise-Adaptor,

resulting in an even smoother sound signature due to the increased offset.