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Be Quiet! Silent Wings PWM (BL023) and USC (BL013)

The Silent Wings PWM (BL023) and USC (BL013) from be quiet! are among the most interesting products in this review. They come in cardboard boxes with a flap and a cutout in the front side.


There is exhaustive information about the product on each box. The PWM (BL023) kit includes screws and spacers whereas the USC (BL013) model is equipped with two PATA power adapters and screws.


These Silent Wings fans are manufactured in China and cost about €18, which is quite a lot. The warranty period is 3 years.

The fans have a slim frame and a 7-blade impeller with riffled blades:


The impeller and electromotor are 112 and 44 millimeters in diameter, respectively. The four spokes are curved in the direction opposite the rotation of the impeller. Three of them are 6 millimeters wide; the cable spoke is 9 millimeters wide. The weight of the fan is 140 grams.

The impeller is nestled within a ring which in its turn is firmly fixed in a square frame of the standard size (120x120x25 millimeters).

The impeller blades have a wavy profile which is meant to minimize noise compared to ordinary smooth impellers, the air flow being the same. Each of these fans has a rotation speed of 1500 RPM and an air flow of 50.5 CFM at 17 to 18.5 dBA of noise. The static pressure is specified to be 1.63 millimeters of water. As their names suggest, the two models differ in that the PWM version features PWM-based speed control while the USC version doesn’t have it.

This difference is indicated on the fans’ stickers:


The two models have identical electrical characteristics. They can start up at 3.5 volts and work in a voltage range of 3.5 to 12 volts. Their peak power consumption is 1.1 watts. I’ve got very similar numbers in my practical tests: both fans started up at 3.3 volts and consumed no more than 1.2 watts. The cable length is 440 millimeters. Most extraordinarily, the Silent Wings PWM (BL023) and USC (BL013) are equipped with fluid dynamic bearings with a record-breaking service life of 300,000 hours. These fans are going to last for as long as 34 years!

Besides everything else, the frames of the Silent Wings fans have silicone bushings to reduce vibrations and noise:

These bushings are not as soft as I would wish.

Here are the test results of these fans:

The Silent Wings fans are better than the Scythe Kama Flow 2 up to a rotation speed of 1200 RPM, but their airflow-to-noise ratio is worse than the leader’s at the higher speeds. Anyway, these be quiet! fans are exceptionally quiet indeed. I guess they even might have been included into the first part of this review where I discussed low-speed and low-noise fans. The Silent Wings series works softly and without any unwanted sounds.

Cool Age 120SX2

In the first part of this roundup I tested a Cool Age Silence Fan 120DX2. Here, I will check out its more advanced cousin called Cool Age 120SX2. Its packaging is compact and transparent from the front:

You can read the specs of the fan from the back of the box. Included with the fan are a speed controller (designed as an expansion-slot bracket for the back panel of the system case), a PATA power adapter and four self-tipping screws.


Take note that the included controller can not only vary the speed of the fan but also turn it off completely. The Cool Age 120SX2 is manufactured is China and costs about $12. Its warranty period is 3 years.

First off, the Cool Age 120SX2 is one of the three fan models in this review to differ from the standard height of 25 millimeters. This model measures 120x120x38 millimeters. Its impeller is white; its frame is black.

The seven-blade impeller seems small but its diameter is actually not much different from other fans, measuring 111 millimeters. Three of the fan spokes are 5 millimeters wide; the cable spoke is 7 millimeters wide. The electromotor is 52 millimeters in diameter, which is indeed larger than with other fans, yet not the largest size in this test session. The Cool Age 120SX2 weighs 259 grams.

The impeller blades are very broad, have a large angle of attack and bend a little in their bottom part.

The ends of the blades are rather thick. The gap between them and the frame is about 3 millimeters. As I’ve said above, the speed of the fan is regulated with a small rheobus. The speed range is 0 to 2000 RPM. The maximum air flow is specified to be 80 CFM at 32 dBA of noise. The static pressure is not listed among the product specs, which is a shame because thick fans usually have a higher static pressure than ordinary 25mm models.

The fan’s large motor bears a sticker:

Below the sticker there is a dual ball bearing with a rated service life of 120,000 hours. That’s quite long. The manufacturer doesn’t specify the start-up voltage but my measurements yield 2.4 volts for that parameter. The Cool Age 120SX2 boasted very low power consumption, about 2 watts only. That’s very low for this bearing type and such a massive impeller. The fan’s 3-wire cable is 260 millimeters long. The speed controller’s cable is about 500 millimeters long.

Let’s see what this heavyweight can do in practical tests:

First of all, the Cool Age 120SX2 was unstable, meaning that it would produce different sounds as I changed its speed. This is a rather annoying effect. On the other hand, if you keep this fan running at its maximum speed all the time, the Cool Age 120SX2 will ensure a strong air flow and, thanks to its thickness, a high static pressure.

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