Inside be quiet!


Exploring Advanced Fan Technologies

We take a brief look behind the scenes what makes be quiet! fans so special.

In the realm of fan technologies, innovation and evolution have a substantial impact on efficiency, noise, performance, and functionality. This article explores the intricacies of smart and impactful features be quiet! uses to stay on top of the game.

Automatic Fan Balancing

Premium brands often invest in fan balancing for smoother running and longer lasting fans. This used to be a manual process for Silent Wings 3. With the introduction of Silent Wings 4 in 2022, we automated the process with an additive fan balancing machine. See the following video for a detailed explanation:

Closed Loop Motor Control for RPM Stability

Without any advanced physics knowledge, one might assume that a fan always runs at its rated RPM, or a percentage of its rated RPM. There are two flaws in this assumption: Firstly, each fan has a variance of usually 5-10% of its maximum RPM. This variance can become higher with age. Secondly, the RPM rating is only valid for freestanding fans with no resistance. If a fan experiences resistance, like a fan grille, heat sink or radiator, the fan speed is reduced, according to the laws of physics. Airflow and fan speed are proportional, so adding resistance or obstructions to a fan’s airflow reduce the its RPM to balance the relationship between airflow and resistance. Maintaining the fan speed would require additional power.

A mainboard’s PWM fan controller follows a simple concept. It sets a certain percentage of the rated maximum speed that corresponds to a temperature sensor, like the CPU temperature, but does not change its duty cycle based on the actual fan speed – even if most mainboards can read out the tachometer signal from the fan. It is pretty much “fire and forget”.

The closed loop fan controller reacts to the tachometer signal, by constantly comparing it to the target speed and adjusting the current and RPM accordingly. This brings several advantages. The user gets stable performance and thermal conditions. On top of that, if a fan is operated in a dusty environment or dirt gets into the bearing by any means, its maximum speed may decrease over time. Since the closed loop controller always reaches for a target speed, the wear effects of a fan can be compensated to an extent. At low RPM, the fan speed usually does not deviate too much from the target. The closed loop becomes relevant at higher speed. That is why it kicks in at around 1,500 RPM for the Pure Wings 3 PWM high-speed fans.

Closed loop fan control has been used in industrial fan design for quite some time and as of publishing this article, Pure Wings 3 PWM high-speed are the only be quiet! fans with this feature.

Waved Grooves in Fan Blades

If you have ever held a be quiet! fan in your hands, you have probably noticed our signature wave pattern on the blades. When we developed our first premium fan in the run-up to 2009, the Silent Wings USC (USC stands for Ultra Silent Concept), we found that wave-shaped grooves on the fan blades improved the performance. They result in steadier airflow and reduce the formation of vortices, which could otherwise cause noise. This seemed to be exactly in line with our brand name and goal to enter the stage of high-performance and especially silent fans.

Our wave-shaped fan blades have been a huge success since their release. Not only do they contribute to improved performance, but also to the iconic, recognizable look be quiet! fans are known for. We refer to fan blades with grooves as "airflow optimized." Look for this phrase in a product's info to know if it has this feature.


Our expectations and requirements for fans are at the highest level. This especially shows when looking at the finer details. Automatic fan balancing, closed loop motor control and the use of waved grooves in the fan blades are key to be quiet! fans’ high performance, increased lifespan, and low-noise operation. If you want to know more about be quiet! fans and which ones are perfect for your system, please check out our fan guide.