By: Jonathan Kwan
August 22, 2009
In the past, we have written three separate articles on five different Noctua products: The Noctua NF-S12-800, NF-S12-1200, NF-R8 review, the Noctua NF-P12 review, and the Noctua NH-U12P review. Now, let's name one Noctua article that I wrote in the past with at least one product that didn't receive a prestigious APH Networks award. The answers: Nope, nope, and... nope. What made us love their products so much? Noctua, an Austrian company that specializes in quiet computing thermal solutions, certainly won't win any beauty contests for the fans and heatsinks they make, nor do they sell the most extreme out-of-this-world cooling solutions. But, what they do make are practical and realistic products that are thoroughly engineered to achieve the best real world performance, while maintaining an extremely low level of perceived noise. They are quality, refined products to achieve its primary purpose reliably throughout its life. And while they are certainly not the lowest priced, they offer excellent performance-to-value ratio for your hard earned cash. Plus, looks in this regard aren't even a huge issue in my opinion. As a quiet PC enthusiast, I exclusively used Noctua fans in the past, and still do, for these very reasons. Upon the release of their latest NF-S12B FLX and NF-S12B ULN case fans to replace the NF-S12-1200 and NF-S12-800, what kind of improvements has Noctua made to their legendary products? I picked up both of them and conducted our usual array of synthetic tests, as well as slapping them into our test setup for real world performance measurements. As excited as you are, let's find out how it all went!
Our Noctua NF-S12B FLX and NF-S12B ULN review units came in a small, brown corrugated cardboard box from Noctua's headquarters in Austria. After traveling half way around the world, it was transferred to Canada Post using the XpressPost service when it arrived on Canadian soil. As usual, a delivery note was left in my mailbox, and I went to a local postal outlet around one minute drive away to pick it up. Everything arrived in reasonably good condition, and Noctua installed an appropriate amount of packing material inside the shipping box to ensure everything arrives safely. We cracked open the box and we're off to more photo taking.
Nothing in particular to the Noctua retail packaging has changed. Just like how APH Networks will always have a shade of orange, both the Noctua NF-S12B FLX and NF-S12B ULN's retail box retains an identical design as it always has been in the past. With its distinct burgundy, white, blue, and black color scheme, previous Noctua customers won't have any problems recognizing who is the manufacturer of the new NF-S12B FLX and NF-S12B ULN case fans. A custom shaped window is shown in front revealing parts of the fan itself, along with one of the four included vibration dampeners. Model information and company logo along with Noctua's website is printed in front as well.
Thanks to their uniform packaging, we have had no problems in what to expect right out of the box. Each fan is packed into a slide-out clear plastic tray with a matching cover; with four vibration dampeners in its own position on the side, and the resistor cables, 3-pin to 4-pin Molex converter, and four mounting screws at the top. At the back of the retail box is a flap that's held closed by a Velcro piece to reveal additional information regarding the Noctua NF-S12B FLX and NF-S12B ULN, respectively. It elaborates, with diagrams and descriptions, on aspects such as the Noctua NF-S12B's beveled blade tips, airflow/noise and pressure/noise ratio graphs, comparison to the original NF-S12 series fans, as well as their SSO bearing technology. All this information can be found on Noctua's website as well.
Before we move on, let's take a look at the specifications of each product, as obtained from Noctua's website:
Noctua NF-S12B FLX
Size: 120x120x25 mm
Bearing: SSO-Bearing
Blade Geometry: NF-S12B Blade Design with BBT
Rotational Speed (+/- 10%): 1200 RPM
Rotational Speed with L.N.A. (+/- 10%): 900 RPM
Rotational Speed with U.L.N.A. (+/- 10%): 600 RPM
Airflow: 100,6 m³/h
Airflow with L.N.A.: 75,8 m³/h
Airflow with U.L.N.A.: 49,2 m³/h
Acoustical Noise: 18,1 dB(A)
Acoustical Noise with L.N.A.: 10,6 dB(A)
Acoustical Noise with U.L.N.A.: 6,2* dB(A)
Static Pressure: 1,31 mm H2O
Static Pressure with L.N.A.: 0,76 mm H2O
Static Pressure with U.L.N.A.: 0,34 mm H2O
Input Power: 1,2 W
Input Current: 0,1 A
Voltage Range: 12 V
MTBF: > 150.000 h
Warranty: 6 years
You will receive the following out of the box:
1x Noctua NF-S12B FLX
1x Ultra-Low-Noise Adapter (U.L.N.A.)
1x Low-Noise Adapter (L.N.A.)
4x Vibration Compensators
1x 3 to 4-Pin Adapter
4x Fan Screws
Noctua NF-S12B ULN
Size: 120x120x25 mm
Bearing: SSO-Bearing
Blade Geometry: NF-S12B Blade Design with BBT
Rotational Speed (+/- 10%): 700 RPM
Rotational Speed with U.L.N.A. (+/- 10%): 500 RPM
Airflow: 56,9 m³/h
Airflow with U.L.N.A.: 38,2 m³/h
Acoustical Noise: 6,8* dB(A)
Acoustical Noise with U.L.N.A.: 5* dB(A)
Static Pressure: 0,44 mm H2O
Static Pressure with U.L.N.A.: 0,23 mm H2O
Input Power: 0,6 W
Input Current: 0,05 A
Voltage Range: 12 V
MTBF: > 150.000 h
Warranty: 6 years
You will receive the following out of the box:
1x Noctua NF-S12B ULN
1x Ultra-Low-Noise Adapter (U.L.N.A.)
4x Vibration Compensators
1x 3 to 4-Pin Adapter
4x Fan Screws
Shown in the photo above are the Noctua NF-S12B FLX and NF-S12B ULN, respectively. Both fans appears to be physically identical other than the sticker in the middle, which means that it incorporates standard Noctua's color scheme of peach and burgundy-ish brown color. While this is a demonstration of consistency among the whole Noctua fans product line, as well as a trademark Noctua design, stylistically this color scheme may not appeal to everyone. It sure stands out in many windowed cases -- whether positive or negative -- but it would be excellent if Noctua offered different color combinations, such as utilizing the tried-and-true black as an alternate choice. The downside to that is that it may appear too generic.
While I mentioned their identical physical appearance attributes (Again, other than the sticker in the middle for the user to distinguish between the two), if you're anything like me, you probably skipped over the specifications section above -- and just wanted a straight answer on what's the difference between the two products without the technical mumble-jumble. If you're not familiar with Noctua's usual naming scheme, 'ULN' means ultra low noise as they usually denote in their resistor cable names, while FLX is just a three letter abbreviation 'flex'. That said, I'll give you a straight answer right now: The NF-S12B FLX has a maximum rotational speed of 1200rpm @ 12V, while the NF-S12B ULN has a maximum rotational speed of 700rpm @ 12V. It's quite logical because the ULN version spins slower, therefore quieter; while the FLX edition can spin at a higher RPM for performance, but undervolted with the included adapters to a lower RPM for quietness -- therefore more 'flexible'. Other than that, they are pretty much the exact same thing.
This probably explains why there is a slight difference in included accessories between the Noctua NF-S12B FLX and Noctua NF-S12B ULN. The FLX includes both an LNA (Low Noise Adapter) and an ULNA (Ultra Low Noise Adapter) cable, while the ULN version only includes an ULNA adapter for ultra ultra low noise. These resistors are color coded as well -- the black cap is an LNA adapter, while the blue cap is an ULNA adapter for the ULN version, and white cap is an ULNA adapter for the FLX version. The only things I want to see are sleeved resistor cables, just like the attached fan cables, as I was since the very beginning haha.
The LNA and ULNA adapter brings the Noctua NF-S12B FLX from its 1200rpm maximum to 900rpm and 600rpm, respectively; while the ULNA adapter on the Noctua NF-S12B ULN straps it down to 500rpm from its maximum 700rpm. The LNA and ULNA adapter on the NF-S12B FLX caps it to much more reasonable RPMs than its predecessor, the Noctua NF-S12-1200, which definitely justifies its FLX name. There's virtually no acoustical noise difference between 600rpm and 500rpm as far as I'm concerned, and very little difference between 900rpm and 700rpm as far as Noctua fans go. Therefore, in my opinion, the FLX version should probably accommodates the needs of most quiet PC enthusiasts. We'll go over this in the Tests section in just a short moment.
As seen in the photo above, the attached fan cable is sleeved -- which looks and feels great. That said, the most important thing that most people would be interested in is the new blade design that accounts for its major improvements. Back in 2006, the Noctua NF-S12 incorporated a straight-blade design. Fast forward to 2009, we've got what Noctua calls the Beveled Blade Tip. What is this, and what is improved compared to the original Noctua NF-S12 fans?
One of the biggest challenges to a noise optimized product is to provide a high level of airflow to noise ratio, and even both of these cannot be objectively measured at all times. The most common unit of objective measurement is CFM (cubic feet per minute) of air for airflow, and dB noise, respectively. We will go over how application and CFM is related with regards to its standard measurements, but let's discuss perceived noise first.
dB (Decibels) is a logarithmic unit of sound intensity. While it provides what appears to be an objective measurement for the most part, it should be noted that perceived noise levels to the human ear, and actual sound intensity, could result in very different things. Human ears are more sensitive to particular frequencies, and when those particular frequencies are emitted from its source, it may appear louder than its numbers suggest. That same can be said vice-versa -- frequencies that human ears are less sensitive to can actually have louder dB measurements from a sound meter, yet the human ears does not perceive it to be as loud as the numbers suggest. Other factors such as turbulence noise are often not measured correctly, therefore, while it usually provides a good reference, it does not necessarily reflect real life performance.
To achieve improved airflow to noise ratio as well as static pressure over the original NF-S12 series fans, Noctua modified the NF-S12's blade geometry as seen in our NF-S12B series fans. As you can see in the photo above, the leading edge (Long side of each blade) is now closer to the edge of the fan frame, while the beveled blade tips shortened the length of the opposite side to increase the tip clearance. By reducing the tip clearance on one side, combined with the use of its beveled blade tips, this permits an increase of surface area of each fan blade while mitigating the increased noise problems associated with the motor. Noctua quotes an "[increase of] noise emission due to critical rotor-stator interaction". What this really means is that in a context of aerodynamics, the rotor is the impeller, and the stator is the frame of the axial fan. By increasing the length of the blades at the leading edge, while implementing a beveled blade structure at its curve, this actually increases the average distance between the blade edge and frame at the outer edge where its relative velocity is at the highest. By doing this, Noctua cleverly combined the advantage of reducing the fan's frame clearance, as well as maximizing room between the drive motor parts and the blade tip. Noctua claims that this would "[achieve] up to 10% improvement both in airflow to noise and pressure to noise ratio."
Noctua continues to implement their highly regarded SSO bearing in the NF-S12B FLX and NF-S12B ULN case fans. The self-stabilizing oil pressure bearing includes an additional magnet which ensures immediate stabilization of the rotor upon startup, which reduces the gyro effect, and increases its reliability in the long run. The additional supporting magnet permits increased precision of axis centering within its bearing shell, which contributes to a reduction of resistance, abrasion, and noise emission, according to Noctua. An updated version of their Smooth Commutation Drive (SC-Drive), aptly named SD-Drive 2, decreases switching noise for overall smoother operation by streaming constant power to the fan's motor to minimizing irregular noise in the transition. Torque is more constant in the DC brushless motor, and current switching is more consistent to reduce acoustical noise.
With regards to the application and CFM, it is generally optimal to have a fan to have a high air volume flow rate -- but as aforementioned, pure CFM values are limited to an extent with regards to its indication on fan performance. It's not completely about how much air in can move per minute quantitatively, but equally as important is how it is executed in reality. Airflow to noise ratio is an essential factor as mentioned earlier. Static pressure is also very important depending on application. High resistance applications such as dense fins on a large heatsink requires high static pressure as offered by the Noctua NF-P12 we've reviewed last year, while case fans needs less static pressure and faster airflow as offered by the Noctua NF-S12B FLX and NF-S12B ULN in this review. Its differences in application is like a large truck that has a diesel engine with lots of low end torque for towing, compared to a sports car with a high revving gasoline engine with lots of power to beat around the track -- they are simply designed for different purposes, so choose the one appropriate for your needs!
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The Tests
Using our tried-and-true APH proprietary 'scientific' method for measuring fan performance we devised back in 2007, it's no surprise that we're using it for this review as well. While it is not exactly the most objective method you can use (No kidding haha), there's a few attributes of fan performance that we can obtain clearly from our observations: Airflow, airflow consistency, and amount of static pressure generated. It visually portrays characteristics of each fan.
Noctua claims that at 1200rpm, the NF-S12B FLX fan produces 18% more airflow and 14% more static pressure compared to the NF-S12-1200 spinning at 1300rpm. Since it runs 100rpm slower, it is also 1dB quieter, according to Noctua. As far as the NF-S12B ULN goes, it generates 13% more airflow and 16% more static pressure than the NF-S12-800. Again, these information are the ones provided from Noctua. It seems to us that low RPM performance has been increased very significantly from the data provided.
From our tissue paper test above, it's very obvious that the Noctua NF-S12B FLX (Shown on the left) moved much more air than the Noctua NF-S12B ULN (Shown on the right), since the NF-S12B FLX spins almost twice as fast as the ULN version by default. The FLX at full speed provided tons of airflow as well as relatively adequate static pressure to keep the inside part of the tissue floating in the air, while keeping its end off the ground, thanks to an abundance of fast moving and stable air. As always from Noctua, airflow is very consistent, and we noticed very little fluttering.
The NF-S12B ULN also has very interesting characteristic to mention. As Noctua themselves claims that it provides much improved low RPM static pressure and airflow compared to its predecessor, it is certainly held true in our tests. There's not a lot of fast moving air to keep the ends up, but both airflow and static pressure is extremely consistent for what it gives to keep at least half of the tissue up. We noticed almost zero fluttering, as it just held that position as if it's a fixed position.
Image taken from another angle, for improved clarity.
Perceived sound is another very important aspect, as we have mentioned earlier with regards to perceived noise versus decibel measurements. However, limitations of this test involves subjective measurement of the reviewer; while one reviewer will tell you it's very quiet, it's entirely plausible that another will claim it's very loud. Throughout the last few years, I have developed my personal subjective perceived sound scale to make some objectiveness out of this matter -- the same measurements has been applied to products ranging from power supplies to video cards. To ensure accuracy, I have several reference devices to make sure my ears are in line at all times. Otherwise, you'll just need to have faith in me, and I believe that based on other noise factor reviews I've completed in the last, I hope I am worthy of this claim!
In conjunction with the resistor cables that slows down the fan RPM, I have thoroughly tested each case fan in detail. Each fan was tested independently in a quiet room, with power supply isolated, to ensure accuracy. On a scale from 0-10 where 0 is the silent and 10 is the loudest, I found the Noctua NF-S12B FLX to be pretty noticeable at full RPM -- gaining a score of 4.0-4.5 on the scale. With the LNA adapter, I would rate it to be 1.5. It is audible at very close ranges. With the ULNA adapter, I would rate it to be 0.5 -- even if you put your ears next to it, all you'd hear is a very silent hum of the motor.
For the Noctua NF-S12B ULN fan, it is already very quiet at 700rpm, gaining a 0.5-1.0 score on the scale. It is very minutely quieter with the ULNA adapter that drops it to 500rpm; which I would also give it a 0.5. It's generally advisable to spin it at 700rpm, since the difference would be zero at a short distance. I had to be very picky to even try to perceive the difference.
Minor clicking noises were noted, but again, you have to listen very closely -- and it's already a noticeable improvement over the original SC-Drive design; the SC-Drive 2 proves to be smoother and less clicky. That's interesting to say, because none had transitioning noise once installed in a computer anyway.
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What Noctua did right here, is actually quite an achievement. They took what already was one of the best case fans in the market, and made them even better! By modifying the blade tips, it improved the amount its fan's capable airflow, as well as static pressure, while dropping noise levels all at the same time. Parallel to that is their improved the motor design to perfect its details for a series of truly refined case fans for every quiet PC enthusiast. Noctua has always put forth a statement that, just because you are a quiet PC enthusiast, does not mean you have to compromise anything. I tend to stick to the same philosophy when I build my main desktop computer, maybe this is the reason why Noctua has always been, and continues to be with the Noctua NF-S12B FLX and NF-S12B ULN, my fan manufacturer of choice! If they offer better color choices, along with other minor changes we've talked about in this review, it would be excellent. While the Noctua NF-S12B FLX is honestly pretty audible (For a quiet PC enthusiast anyway) at full RPM, you can easily drop its voltage to cap it to different RPM profiles with the included adapters. That's not to mention that it caps it to much more reasonable RPMs than its predecessor to make it worthwhile. Through this, it offers a high level flexibility to accommodate different needs, as its name suggests. This is especially convenient if you're like me and let the motherboard control its speed -- at normal loads, the fan spins at an optimal 700-800rpm. But once the computer goes under load and moves above a certain temperature threshold, the fan spins up to maximize cooling efficiency. With regards to the Noctua NF-S12B ULN, it certain grasped what it means to be a quiet case fan. It's pretty much the exact same thing as the Noctua NF-S12B FLX with a voltage cap, so while I am glad that Noctua offers different choices to the consumer, I don't see a reason why you shouldn't pick the FLX version and cap it, and get the ULN instead. Whatever your justifications may be, you definitely cannot go wrong with either of the two -- they are refined, high performance, reliable, quality, and quiet case fans for the noise conscious computer enthusiast!
Special thanks to Jakob over at Noctua for making this review possible.
Noctua NF-S12B FLX
APH Recommended Award | APH Review Focus Summary:
8/10 means Definitely a very good product with drawbacks that aren't likely going to matter to the end user.
-- Final APH Numeric Rating is 8.0/10
Please note that the APH Numeric Rating system is based off our proprietary guidelines in the Review Focus, and should not be compared to other sites.
Noctua NF-S12B ULN
APH Review Focus Summary:
7/10 means Great product with many advantages and certain insignificant drawbacks; but should be considered before purchasing.
8/10 means Definitely a very good product with drawbacks that aren't likely going to matter to the end user.
-- Final APH Numeric Rating is 7.1/10
Please note that the APH Numeric Rating system is based off our proprietary guidelines in the Review Focus, and should not be compared to other sites.
