be quiet! Silent Wings Pro 4 140mm PWM Fan - BL099 2400RPM
be quiet!
be quiet! Silent Wings Pro 4 140mm PWM Fan - BL099 2400RPM
The be quiet! Silent Wings Pro 4 140mm PWM Fan is a high-performance case and radiator fan for builders who need adjustable cooling power without sacrificing acoustics. A three-position speed switch lets you tune maximum RPM between 1,100 and 2,400 rpm depending on your workload, while optimised blade geometry and a funnel-shaped outlet deliver high air pressure even at lower speeds.
Why this product
Speed switch for three cooling modes
Medium-speed (1,100 rpm) for everyday use, high-speed (1,900 rpm) for sustained loads, or ultra-high-speed (2,400 rpm) for extreme cooling demand. Slide the switch on the fan housing to change modes without touching BIOS or software.
High static pressure for radiators and heatsinks
A tight blade-to-frame gap and funnel outlet generate 3.64 mm H₂O of static pressure at full speed, allowing it to work effectively against the resistance of dense cooling hardware.
Three mounting styles included
Radiator corners (pre-installed), anti-vibration dampers for chassis mounting, and plastic standoffs give you the right connection method for your setup.
Fluid-dynamic bearing rated for 300,000 hours
The advanced FDB bearing and low-vibration 6-pole motor are engineered for longevity and quiet operation even at peak RPM.
36.8 dB(A) at maximum speed
Even at 2,400 rpm and full airflow, it remains audible but not intrusive—useful when you need cooling power but prefer to manage noise.
- Size140 × 140 × 25 mm
- Speed range1,100 to 2,400 rpm (three fixed modes)
- Airflow (max)97.41 CFM (165.5 m³/h)
- Static pressure (max)3.64 mm H₂O
- Noise (max)36.8 dB(A)
- Connector4-pin PWM
- BearingFluid-dynamic (FDB)
- Lifespan300,000 hours
- SKUBEQ-939
- EAN4260052188910
- 4-pin PWM connector: works with any motherboard PWM header or fan controller supporting 12 V PWM fan input.
- 140 mm mounting holes: fits standard 140 mm case fan and radiator mounting points.
- Radiator-optimised design: equally at home on tower coolers, AIO radiators, or case intake/exhaust positions.
- Speed switching is hardware-based (manual slide on the fan body), not software-controlled—you must physically access the fan to change modes, so consider placement before installation.
Best for
- Radiator cooling in high-end air or water-cooled builds
- Users who want adjustable performance without BIOS tweaking
- Builders prioritising low vibration and quiet operation at part load
- Systems where static pressure matters: dense radiators, heatsink fins, or restrictive cases
Trade-offs
- RPM-limited builds: If your case or cooler requires very low speeds (under 1,100 rpm), the medium-speed mode is the lowest this fan offers.
- Silent-at-all-costs systems: 36.8 dB(A) at full speed is respectable but not whisper-quiet; passive cooling or larger-diameter, slower fans may be quieter overall.
- Automatic speed control only: The hardware speed switch requires manual adjustment; there is no PWM voltage-based ramp between the three modes.
LEGENDARY SILENCE, EPIC PERFORMANCE AND FEATURES
Silent Wings Pro 4 140mm PWM is the most progressive, performant and versatile fan by be quiet!
The fan blades are what makes a fan. It is for this reason that the fan blades of Silent Wings Pro 4 140mm PWM have been developed newly from scratch. The new blade arrangement enables a performance second to none for all possible operations. Be it in a case, on radiators or heat sinks.
Silent Wings Pro 4 140mm PWM makes for extraordinary air pressure and therefor, significantly increases the system's performance. The decreased distance between the fan blades and the frame enables an extraordinarily high air pressure. By that, the Silent Wings Pro 4 140mm PWM allows the user to run even the most demanding applications.
The speed switch makes switching between medium, high-speed and ultra-high-speed of maximum RPM levels quick and easy. The Silent Wings Pro 4 140mm PWM alters its application with a simple slide to the right. Medium-speed is suitable for any operation that requires regular cooling performance. High-speed lets the fan spin faster, providing more cooling power. Ultra-high-speed ultimately offers enough rpm to cool even the most demanding hardware in high-end PC builds.
Silent Wings Pro 4 140mm PWM has 3 mounting options in the scope of delivery. The pre-installed radiator corners are specially designed for radiators on which the incomparable performance of this high-end fan completely shines. On the other hand, for chassis use, the anti-vibration mounting is the first choice as they reduce vibrations to a minimum. The plastic mountings round up the scope.
The advanced fluid-dynamic bearing (FDB) enables a super long fan life of up to 300,000 hours.
Fan
| Brand | be quiet! |
|---|---|
| Model | Silent Wings Pro 4 140mm PWM |
| Part number | BL099 |
| Size | 140 × 140 × 25 mm |
| Connector | 4-pin PWM |
| Cable length | 500 mm |
| Weight | 0.258 kg |
| Mounting options included | Radiator corners, anti-vibration dampers, plastic standoffs |
Performance
| Speed range | 1,100 to 2,400 rpm (three fixed modes) |
|---|---|
| Speed modes | Medium (1,100 rpm), high (1,900 rpm), ultra-high (2,400 rpm) |
| Airflow @ 100% PWM | 97.41 CFM (165.5 m³/h) |
| Static pressure @ 100% PWM | 3.64 mm H₂O |
| Bearing type | Fluid-dynamic (FDB) |
| Motor type | 6-pole, 3-phase |
Acoustics & power
| Noise level @ 100% PWM | 36.8 dB(A) |
|---|---|
| Lifespan | 300,000 hours |
Shipping
All our products are shipped from the United Kingdom within 24 to 48 hours of purchase. See our Shipping and Returns page for full details.
Returns
- Tech Syndicate offers a full money-back guarantee on all purchases made in our store. If you are not satisfied with your purchase, we will provide a full refund, no questions asked.
- Refunds are available within 45 days of delivery.
- After the 45-day period you are no longer eligible for a refund, so we encourage you to try the product within the first few weeks to make sure it fits your needs.