14 cm PC fan Noctua NF-A14X25R G2 PWM, 140 x 25 mm, 12 V, 1500 RPM, 155.6 m³/h, 2.56 mmH2O

The Noctua NF-A14x25r G2 PWM Sx2-PP is a set of two 140 mm round-frame fans optimized for push-pull operation on large tower coolers such as the NH-D15(S) or NH-U14S. The pair is speed-offset by approximately +/-25 rpm to avoid acoustic interference (beat frequencies, intermittent vibrations or humming) that can occur when two identical fans run at the same constant speed. The offset is implemented via the fans' etaPERF™ motor and NE-FD6 driver IC, which provide very precise speed control and extra torque headroom (SupraTorque™) so each fan maintains the intended RPM even under significant flow resistance.

Advantages

The Sx2-PP bundle maintains the same overall cooling performance as two identical NF-A14x25r G2 PWM fans while reducing the risk of audible artifacts in push-pull configurations. The NF-A14x25r G2 uses a Progressive-Bend impeller with Flow Acceleration Channels, winglets and a Centrifugal Turbulator hub for improved efficiency and lower noise under back pressure. Its ultra-tight 0.7 mm tip clearance, Sterrox® LCP impeller material, AAO frame with Stepped Inlet Design and Inner Surface Microstructures, SSO2 bearing, metal bearing shell and advanced etaPERF™ motor with NE-FD6 all contribute to consistent performance, durability and low acoustic signature. The set includes a Low-Noise Adaptor and extension cabling, and the fans offer wide PWM speed control from 1500 to 300 RPM with stop-at-0% functionality for semi-passive setups.

Suitable for

• Push-pull configurations on 140 mm heatsinks (e.g., NH-D15(S), NH-U14S)
• Radiator use in closed-loop liquid cooling systems where reduced audible interaction is desired
• High back-pressure environments requiring stable RPM under load
• Quiet PC builds that benefit from PWM speed control and L.N.A. throttling

Key specifications

• Fan diameter: 140 mm
• Maximum speed: 1500 RPM (1250 RPM with supplied Low-Noise Adaptor)
• Airflow: 155.6 m³/h (manufacturer rating for single fan)
• Speed range: 300–1500 RPM (PWM); stops at 0% PWM
• Bearing: SSO2 (self-stabilizing oil-pressure type)
• Tip clearance: 0.7 mm
• Connector/cabling: 4-pin PWM, 20 cm primary cable, 30 cm extension, 4-pin Y-cable
• Protection: reverse polarity, over-voltage, over-current, locked rotor/overload protection
• Certifications: CE, TÜV, UKCA, UL (meets EN 62368-1, EN 55035, EN 55032, UL-507)
• Warranty: 6 years; MTTF > 150,000 hours

How to use

Install the two fans in a push-pull arrangement on a compatible 140 mm-class heatsink, aligning one fan to push air through the fin stack and the second to pull air out. Connect each fan to a PWM-capable header or use the included Y-cable to control both from a single PWM header. Use the Low-Noise Adaptor if you prefer a lower maximum speed or manually adjust PWM duty cycle via motherboard fan control or a separate fan controller. If acoustic tuning is required, slightly reduce the PWM duty cycle of the fan designated as PPA (the slower-tuned fan) to increase the offset and further minimise audible beat phenomena.

Recommendations

The +/- ~25 rpm factory offset is designed to avoid beat-frequency artifacts in push-pull setups. If you still perceive tonal interaction, increase the offset by reducing the PPA fan's PWM duty cycle or apply the Low-Noise Adaptor to that fan for an even smoother acoustic signature.