be quiet! has launched a new fan named Silent Wings 4. There are multiple versions in each category of 120mm and 140mm. We have earlier reviewed the Silent Wings 4 140mm PWM High-Speed fans and found their performance quite remarkable. Those fans were tested on the Alphacool SuperNova 1260 radiator and they are still in use on that radiator.

This time around we are testing the premium, top-of-the-class fans in this range named Silent Wings 4 PRO. The PRO versions are available in 120 and 140-mm sizes. We have got both variants for testing.

Some of the characteristics of the new Silent Wings Pro 4 include:

  • Silent Wings Pro 4 PWM is the most progressive, performant, and versatile fan by be quiet!
  • Optimized fan blades for the highest performance on radiators and heat sinks
  • Speed switch allows changing maximum PWM speed between medium-speed, high-speed, and ultra-high-speed (up to 3000 rpm for the 120mm and 2400 rpm for the 140mm)
  • Small tip clearance and a fan frame with a funnel-shaped air outlet for extremely high air pressure
  • Virtually inaudible operation at regular speed
  • 6-pole fan motor and fluid-dynamic bearing for less vibration and very smooth operations
  • Individual mounting systems for use as a case fan or with a radiator
  • 5-year manufacturer warranty


Silent Wings PRO 4 120mm PWM Euro 31.90
Silent Wings PRO 4 140mm PWM Euro 32.90




Specs 120mm


Specs 140mm

Packaging and Unboxing

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The fans are shipped inside a paperboard packing box in the typical black color theme from be quiet!. Be quiet! has highlighted the following:

  • Legendary Silence
  • Epic Performance
  • Features

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The specifications are printed on the backside of the main packing box. The fans are developed in Germany.

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There are two more boxes inside the main packing box. The top box has the label Accessories and it contains the screws and mounting corners. The bottom box has the fan itself.

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The above picture shows the fans in their box.

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A user guide is provided in each box.

Closer Look

Let’s take a look at the fans. Since both versions have the same design, we are showing pictures of both at the same time.

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The Silent Wings Pro 4 are available in 120mm and 140mm sizes. These are all black color fans. Be quiet! has focused on delivering the ultimate performance that one would expect coming from the new generation. The new design has reduced the clearance of the blades’ tips from the boundary which is what Noctua did with NF-A12x25 series fans.

The tip clearance plays a significant role when it comes to sustaining the high pressure while delivering the flow as it reduces the turbulence. The 120mm fan has 9 blades whereas the 140mm fan has 7 blades. These blades have textured surfaces in an altered layout. The center of the fan has a large diameter. The fan sticker is also in black color having the brand name on it. The main frame is circular with detachable mounting corners.

The main feature of these PRO fans and other Silent Wings 4 series fans is the detachable mounting corners. For some time, be quiet! has stick with their traditional design where there is a space on the mounting corners which could lead to air leakage. This time around, they have come up with different corner mounts each serving a specific purpose like for use on a radiator or the PC Case, etc. Only the PRO series fans come with a total of 3 style corners. The 140mm PWM High-Speed fans which we tested have two sets of corners.

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The above picture shows the close-up of the mounting corner. The fans come with pre-installed corners specially designed for the radiator. There are cut-to-size anti-vibration pads on the corners. These pre-installed corners give these fans a square shape that looks good in person. These fans bear some weight; which you can tell by holding them in hand.

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The above picture shows the other two sets of mounting corners. We have a total of three sets:

  • Radiator corners [pre-installed]
  • Anti-vibration corners for the case
  • Plastic corners which are probably for the heatsink

There are push pins and self-tapping screws provided as well.

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The above picture shows all three sets of corners. The right-side corner mounts use push-pins for the installation. The left ones are for the heatsink used.

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The removal and installation of the mounts are convenient. There are two latches on each side of the corner mount. Pressing them at a time would release the mount which then can be taken off. Similarly, place the corner mount on the fan corner and press them for installation.

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The above picture shows both fans after removing the corner mounts.

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The above picture shows the other two corner mounts installed on the fan.

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The mounts have Corner Type A and B carved on them. This makes it easier to identify when installing the mounts. The Corner Type-B is to be installed on the fan’s corner where the PWM power cable is coming out. There is a cut-out provided on this corner through which the cable is passed during the installation.

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The above picture shows the frame of the fan. The fan’s frame is sturdy and the overall weight of the fan is more than the other standard 120mm and 140mm fans in the market. There are two arrow markers on the side of the frame. These show the direction of airflow and the direction in which blades would spin. The opposite side of the frame has be quiet! branding over it.

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The backside of the fans shows a four-arms assembly with one arm widened to provide a pathway for the wires. Looking closely, you will spot a slider button. This is there to switch among the 3x pre-defined speeds on these fans.

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The above picture shows the slider button located on the backside of the fan. It has three labels:

Silent Wings 4 PRO 120mm Silent Wings 4 PRO 140mm
Medium (M) Up to 1600 RPM Up to 1100 RPM
High-Speed (HS) Up to 2500 RPM Up to 1900 RPM
Ultra High-Speed (UHS) Up to 3000 RPM Up to 2400 RPM

The above table lists the speed range under each speed dial. I would personally, set the fan speed to UHS and use the PWM control for speed regulation.

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This new connector on the power cable is something new and speaks for itself. It is a 4-pin PWM connector with a nicely sleeved cable. Though this design makes the connector bulky in looks, it is indeed a better implementation as we now have a handle to grab for installing and removing the connector.

be quiet! is using Fluid Dynamic Bearing in these fans having a life span of 300,000 hours. These bearings reduce the vibration which helps in reducing the overall noise output. These fans are using 6-pole, 3-phase motor.

The salient specifications of the fans are:

Silent Wings 4 PRO 120mm Silent Wings 4 PRO 140mm
Dimension 120x120x25mm 140x140x25mm
Fan Speed at 100% PWM 3000 RPM 2400 RPM
Noise Level at 100% PWM 36.9 dB(A) 36.8 dB(A)
Airflow at 100% PWM 83.9 CFM 97.41 CFM
Air Pressure at 100% PWM 5.31 mmH₂O 3.64 mmH₂O
Voltage Range 7~13.2VDC 7~13.2VDC
Input Power 3.6W 6.0W
Input Current 0.3A 0.5A


The following test bench is used for thermal performance testing: –

  • AMD Ryzen 7 7700X [5.2GHz, 1.260V]
  • DeepCool LT520
  • XPG Lancer RGB 32GB @ 6000MHz DDR5
  • MSI GeForce RTX 3090 Gaming X Trio
  • Sabrent Rocket 4 Plus 2TB NVMe SSD [For OS and Data]
  • bequiet! Straight Power 11 850W Platinum PSU
  • Thermaltake Core P6 TG Snow Edition in an open frame layout

CINEBENCH R23 is used to stress the CPU for 30 minutes. The system is left idle for 10 minutes to record the idle temperature. The CPU (Tdie) temperature is reported in the graph. For comparison, we have the DeepCool FK120 120mm and GIGABYTE 140mm fans.

Please note that not every run of the stress test may yield the same result. This could well be due to many factors like mounting pressure, thermal paste application and varying ambient temperature. Not to mention the silicon differences even among the same category of chips. Hence, it is pertinent to mention the testing methodology along with the specifics.

The fans were run at Medium, High-Speed, and Ultra-High-Speed dials for each run. Let’s take a look at the result.

Silent Wings 4 PRO 120mm PWM Idle Temps

Idle Temps using Silent Wings 4 PRO 120mm fans.

Silent Wings 4 PRO 120mm PWM Load Temps

Load Temps using Silent Wings 4 PRO 120mm fans.

Silent Wings 4 PRO 140mm PWM Idle Temps

Idle Temps using Silent Wings 4 PRO 140mm fans.

Silent Wings 4 PRO 140mm PWM Load Temps

Load Temps using Silent Wings 4 PRO 140mm fans.

The new be quiet! Silent Wings 4 PROI 120 and 140mm fans have shown impressive performance.

Here is a table showing RPM range and corresponding airflow and speed measurements of the be quiet! Silent Wings Pro 4 120mm PWM  fan:

PWM Duty Cycle (%age) Speed (RPM) Airflow (CFM)
20 1290 46
30 1516 55
40 1726 63
50 1950 71
60 2177 79
70 2385 85
80 2566 92
90 2755 99
100 3000 106
Medium Speed Dial 1642 60
High-Speed Dial 2528 90
Ultra-High-Speed Dial 3000 105

We are taking the airflow reading by placing the instrument closer to the fan. The values would vary depending on the distance between the anemometer and the fan.


Silent Wings 4 PRO 120mm PWM

Speed (RPM) Noise Level [ dBA() ]
Medium Speed Dial 1642 40
High-Speed Dial 2528 49~50
Ultra-High-Speed Dial 3000 53

The ambient noise level is calibrated at 32 dB(A). The fans are loud at full speed but they are not as loud as the Noctua iPPC fans at their full speed and this is where be quiet! has done some magic to offer a true cooling potential without that high noise output.


We have a new spearhead in the cooling department from be quiet! Meet the new Silent Wings 4 series which is the next generation of high-performance fans from the manufacturer taking over the game from Silent Wings 3. The new fans are available in 120mm and 140mm sizes in various configurations. There is also a PRO version of the fans in this series which represents the pinnacle of high-end cooling fans from be quiet! We have tested the Silent Wings 4 PRO 120 and 140mm PWM fans.

These fans have a good build quality and we have observed that these fans weigh a bit more than what we have seen on the other 120mm size fans in the lab. The salient feature is the new altered blade layout and tip clearance from the border of the frame. The gap is narrowed which would result in higher air pressure on the edges.

The second striking difference is the detachable mounting corners. be quiet! has provided 3 sets of corner mounts for the different scenarios. The fans come with the radiator mounts pre-installed. These mounts give the fan a square frame finish which looks quite elegant and premium. The other two sets include an anti-vibration corner which is what we have been seeing in the previous generation of be quiet! fans. The other set is of the plastic corner mount. be quiet! has provided screws and push-pins.

These fans are using Fluid Dynamic Bearings having a life span of 300,000 hours and a 6-pole, 3-phase motor which produces less vibration and is heat efficient as well. The PWM connector of these fans is something to speak of. It does look premium and be quiet! has used a nice sleeved cable as well. This connector makes plugging in and out convenient.

These fans feature a speed dial slider on the back of the fans. There are three-speed dials.

Silent Wings 4 PRO 120mm Silent Wings 4 PRO 140mm
Medium (M) Up to 1600 RPM Up to 1100 RPM
High-Speed (HS) Up to 2500 RPM Up to 1900 RPM
Ultra High-Speed (UHS) Up to 3000 RPM Up to 2400 RPM


Please note that if you set the slider to say at M then even at 100% PWM duty cycle, the fan will not go above the speed limit set for that setting which is 1600RPM for the 120mm fan and 1100RPM for the 140mm fan. In my opinion, it would be better to set these fans at UHS dial and control the speed using the PWM function. I am saying this because once these fans are installed and you would want to change the speed, then the fans would need to be removed just to change the speed using the slider.

These fans are rated for up to 3000 RPM for the 120mm fans and 2400 RPM for the 140mm fans. The 120mm fans can’t go below 1200 RPM. The operating voltage range is 7~13.2VDC. The 1200mm fan draws 3.6W using 0.3A at 12VDC whereas the power rating for the 140mm is 6.0W power at 0.5A. The airflow rating is 83.9 CFM with a static pressure rating of 5.31mmH₂O at 12VDC for the 120mm fan. The 140mm fan has an airflow rating of 97.41 CFM with a static pressure rating of 3.64 mmH₂O.

The be quiet! Silent Wings Pro 4 120mm PWM single fan pack has an MSRP of Euro 31.90 whereas the 140mm single fan has an MSRP of 32.90. This is quite a premium price tag but be quiet! offer stands out given the high performance of these fans and the level of customization provided. Plus these fans come with a 5-year warranty. The thermal performance of these fans on the radiator is quite impressive as per our testing. The Silent Wings 4 PRO 120mm and 140mm are loud but not as high as the competition is at almost the same specs rating. This makes these fans a compelling option offer for the enthusiast who wants the best of the best without any compromise.

Thanks to be quiet! for the provision of test units.

Enos Tech Performance Award