BeQuiet! Silent Wings 4 (BL117): A white choice for your case

BeQuiet! Silent Wings 4 (BL117) in detail

The Silent Wings (Pro) 4 represent the pinnacle of computer fan range. The non-Pro variants stand out especially in system positions and are not well suited for radiators. This is by design and in line with the sort of “micro-segmentation” of BeQuiet. In a white design, like the one tested, it will be quite difficult to find other 140 mm fans that are quieter at comparable airflow.

BeQuiet! categorically concentrates the most advanced fans it carries into the Silent Wings (Pro) 4 series. We’ve previously tested two Silent Wings 4 Pro models – the BL098 (120 mm, black) and the BL099 (140 mm, black). In this review we will be discussing the “only” Silent Wings 4. We use the word “only” because in this case, for the first time, we will be dealing with a non-Pro variant, which is accompanied by a number of design differences. Some of them have an impact on cooling performance. And although it can sometimes differ significantly (and be lower), other times you won’t notice the difference too much.

As for the impeller geometry, it is exactly the same with the Silent Wings 4 as with the Silent Wings Pro 4. The foundation lies in the blades with more pronounced leading edge curvature. However, BeQuiet! didn’t overdo it in this regard to keep the blades from being too long and flexible, which could lead to too much vibration due to the PBT composition. This way, the blade stiffness is above average for 140 mm fans thanks to the 2.35 mm thickening (tips) and is suitable for the operating range of 194~1919 rpm.

Please note: With nylon dust filters that don’t have some sort of a reinforced mesh, this fan can get into a collision. The height difference between the frame and the impeller structure is too small and there is a risk of mutual contact resulting in excessive, extremely annoying noise.

The impeller consists of seven blades. With their smaller size, as already mentioned, it is clear that the gaps between the blades are larger (than in 9-blade designs or designs with a larger blade footprint), which naturally has implications for lower static pressures.

Now don’t look at the “absolute” static pressure at zero airflow, in which the nature of the motor’s behavior as a function of environmental resistance is involved, but at the significantly milder situation in an environment on real obstacles. On these, a fan like this will naturally lag behind a “fuller” fan in terms of performance, but the reward may be lower noise. And that is precisely due to the smaller number of blades with less interaction with the airflow.


The surface of the blades is grooved on both sides, which is a characteristic feature of BeQuiet! fans. This suppresses unwanted microturbulence at the intake and, due to the higher friction, also the sliding of air streams along the length of the blades, which occurs to a certain extent due to centrifugal force.

Also included with the accessories are spare, “standard” corners. However, pre-installed are corners optimized for installation in cases. The advantage of these corners is the soft fit, which prevents contact of hard parts through which the vibrations that cause secondary noise (typically from case resonating) would propagate.

The composition of these corners is largely rubber (only the extension that snaps to the frame is plastic) and a rubber insert is applied during installation. This comes from the opposite side of the sheet metal to which the fan is attached. The connecting material is a pin that is installed by pushing in, without the need for any tools. This is why the Silent Wings 4 fans, including the BL117, are optimized towards system cooling, i.e. for mounting in a computer case.

And now to why the Silent Wings 4 isn’t too good for radiators for a change. You can conveniently swap the pre-installed corners for a type designed to be mounted via metal screws (and even long, radiator screws) to make installation possible at all (on a radiator), but the latter is rather leaky. In fact, there are large gaps between these corners and the radiator mounting frame. These reduce the pressure and airflow between the radiator fins. It is similar to making holes in a garden hose. BeQuiet! does have another type of corners – radiator corners – to eliminate these leaks, but these are only included with the Silent Wings 4 Pro, the more expensive variant of the fan (with “Pro” in the designation).

We addressed how these corners increase the static pressure, which also increases the airflow through the radiator in a separate test focusing on this aspect only. It points out that the corners designed for cases also transmit less vibration to the fan frame compared to the “standard” ones. We have also used the “case” corners for most of our tests, except for installations on radiators, with which they are incompatible. On radiators, the fans are already installed through corners referred to as “standard” by BeQuiet.

Note: The Specifications chart, which used to be in the following place, is now on the second page of the article. We have reserved a separate chapter for it because of its growing size and the resulting relatively large height. This separation should thus contribute to better user control, especially on mobile devices with smaller displays.

And one more thing: To navigate through the result graphs as easily as possible, you can sort the bars according to different criteria (via the button on the bottom left). By (non)presence of lighting, profile thickness, brand, bearings, price or value (with the option to change the sorting to descending or ascending). In the default settings, there is a preset “format” criterion that separates 120mm fans from 140mm fans.

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Go for the variant with nine longer blades or seven shorter blades? That’s the question we’ll tackle in this test of the Pure Wings 3 140mm fan. In addition to the different geometries, you can also choose between different speed ranges with differently placed maximums. The high-speed variant has the upper hand, as expected, when it comes to needing to achieve the highest possible airflow. But it also excels in other situations. Read more “More and faster blades, BeQuiet! Pure Wings 3 (BL113)” »


BeQuiet! put all their modern fans in white

Both 120 and 140 mm BeQuiet! fans from the Silent Wings (Pro) 4 and Pure Wings 3 series are now available in an all-white design. So both more expensive and cheaper fans, which have in common a very high airflow per unit of noise. Across the entire price spectrum, you are dealing with some of the most efficient fans you can buy for computers. And not just among the white ones. Read more “BeQuiet! put all their modern fans in white” »


BeQuiet! Dark Rock Elite – The new king of coolers?

I will start this year’s cooler tests with a real treat. I’ve prepared a review of the Dark Rock Elite cooler, the absolute top of BeQuiet!’s range. This is a premium cooler offering very high performance at low noise levels thanks to its sophisticated design in combination with high-end fans. I’m very curious to see how it performs compared to the high-end coolers I’ve had the opportunity to test over the past year. Read more “BeQuiet! Dark Rock Elite – The new king of coolers?” »


Comments (7) Add comment

  1. Is the very low speed characteristics similar to that observed in CPS RZ120?

    This fan would have been much more competitive if it were to have closed corners by default. The corner swapping gimmick doesn’t seem to offer any actual benefit to me, as the vibrations are already low and similar results in dampening could already be achieved by using rubber mounts. They definitely could have saved some cost and/or priced the fan even more competitively by using integrated, closed corners instead of this gimmicky design.

    That said, for users willing to DIY, this should still be a great radiator fan. All you need is some tape to seal up the corners, saving you quite a bit of money.

    1. Yes, if you encounter a lower airflow at the same noise level, a similar characteristic (as with the Silent Wings 4 BL117) is also found in the F5 R120. More fans have this. At such low speeds, the non-aerodynamic sounds must be extremely quiet to leave room to set the speed high enough for leading rankings.

      Replacing the corners of the BL117 is really useful if only just to be able to install this fan on a radiator of a liquid cooler, where the SW4 doesn’t make much sense. Although the SW4 doesn’t need to be smeared too much in this scenario. Sure, due to the significant drop in placement compared to other fans, the urge is there, but at higher speeds it even outperforms the NF-A14. Sure, for a fan with modern geometry it’s more of a failure, but…

      Using tape to seal the corners is a good DIY “trick”. 🙂

      1. How would you compare it to the Pure Wings 3? This fan seems to constantly get outperformed by its cheaper sibling. The Pure Wings 3 does have a lower RPM limit, but there doesn’t seem to be other major disadvantages by going for the Pure Wings instead.

        Now I’m really curious how the high speed, 9-blade version of the Pure Wings 3 performs.

        1. The 140 mm Pure Wings 3 with 7 blades often seems to be a balanced (and a hair more more efficient) solution like the Silent Wings 4 (BL117). Although we have the SW4 in the white variant, which probably tends to be a bit noisier. These small differences (in tonal peaks) do not show up on radiators, where the tested PW3 variant has a significant advantage for obvious reasons (good sealing corners). We are also curious about the 9-blade Pure Wings 3 in 140 mm format. We will probably get to it after the announced Arctic P14 triple fan test (PWM PST, PWM PST CO and Max). 🙂

          The Pure Wings 3 has a MTBF of 60 000 hours, which can be a disadvantage compared to Silent Wings 4 (with 300 000 hours). Lower robustness of critical parts in terms of durability (or change of properties over time) can also be indicated by the smaller impeller hub (of the PW3 BL108) and also at higher speeds relatively higher vibrations (again of the PW3 BL108), which could also indicate higher manufacturing tolerances. Of course, these vibrations could also be due to vibrations on the blades, but I assume they will be composed of several sources. And one of them will be related to the quality level of the impeller centering.

          1. I guess the P14 trilogy will be consecutive releases then.

            It’s a shame that we can’t have a Silent Wings 4 that comes with sealed corners, otherwise we’d have a reliable (and strong performing) 14 cm fan in the ~20$/£ price range that would compete very favourably vs. the Noctua A14 for example. I guess that’s done to prevent cannibalising their sales of their own flagship, but I’m not sure if it’s a smart move given the tough competition…

            1. Yes, the next test will be the P14 PWM PST CO and I will conclude the trilogy (on Monday?) with the Max model.

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