When it comes to the PC Cooling solutions, particularly the air cooling, Noctua is not a new name. They are a premium brand and definitely enjoying the leading position in the market of air cooling. Their air coolers like NH-D15, NH-U14S/12S, NH-L12S, to name a few, are highly popular among the PC users and Noctua takes care of their customers by providing legendary warranty service up to 6 years which speaks of their confidence in their products. Not only coolers but their fans are also highly popular among the water cooling enthusiasts to air cooling requirements and PC airflow. Their iPPC series of fans in 12V and 24V are key pickers for the radiators.

PRODUCT INFO
Noctua NF-A12x25 FLX Fan
Manufacture	Noctua
Available at	View at Amazon

Noctua is known for their typical brown and beige color scheme on the fans and too industrial look on the heatsinks, which are the only gripe that their customers hold but Noctua has addressed these complaints in a perfect manner by launching Chromax series of the accessories for the heatsinks and fans that would allow the users to color coordinate their builds as per the theme yet enjoy the same premium performance that Noctua is known for.

Much was hyped and anticipated for the Noctua’s new generation of the fans which took them whopping 4.5 years into making. But they have finally released their new generation of the fans. The main enthusiast line of these is branded under NF-A12x25 where x25 refers to the 25mm thickness of the fan and 12 here indicate the 120mm size. There are three versions under NF-A12x25 which are PWM, FLX, and ULN. We will be taking a look at their FLX edition of the new fans. The NF-A12x25 FLX is a 3-pin format fan with three speeds settings for full flexibility.

These fans are rated at 2000 RPM max speed and are supplied with Low Noise Adapter and Ultra Low Noise Adapter for 1700 RPM and 1350 RPM speed regulation respectively. These fans represent the pinnacle of the technological advancement as Noctua has done them almost from scratch which is what we have yet to see from other manufacturers. Let’s find out the background story and see how well these fans would perform.

Specifications

Size	120x120x25 mm
Mounting hole spacing	105x105 mm
Connector	3-pin
Bearing	SSO2
Blade Geometry	A-Series with Flow Acceleration Channels
Frame Technology	AAO (Advanced Acoustic Optimisation)
Material	Sterrox® LCP
Rotational Speed (+/- 10%)	2000 RPM
Rotational Speed with L.N.A. (+/- 10%)	1700 RPM
Rotational Speed with U.L.N.A. (+/- 10%)	1350 RPM
Airflow	Airflow 102,1 m³/h
Airflow with L.N.A.	84,5 m³/h
Airflow with U.L.N.A.	64,5 m³/h
Acoustical Noise	22,6 dB(A)
Acoustical Noise with L.N.A.	18,8 dB(A)
Acoustical Noise with U.L.N.A.	14,2 dB(A)
Static Pressure	2,34 mm H₂O
Static Pressure with L.N.A.	1,65 mm H₂O
Static Pressure with U.L.N.A.	1,05 mm H₂O
Max. Input Power	1,68 W
Max. Input Current	0,14 A
Voltage	12 V
MTTF	> 150.000 h
Scope of delivery	*Low-Noise Adaptor (L.N.A.) *Ultra-Low-Noise Adaptor (U.L.N.A.) *3:4-pin power supply adaptor *30cm extension cable *NA-AV2 anti-vibration mounts *Anti-vibration gasket for water cooling radiators *Fan screws
Warranty	6 years

Unboxing and Contents

The fan comes in a premium packaging that definitely deserves an applaud. From marketing perspective, presentation of the product is critical as it could make a difference. The main box is made of the cardboard box and is done in Noctua branding. The front cover is flap over design. On the top side we can see the model of the fan printed. There is a silver color sticker pasted mentioning that it is a 3-pin FLX version. Salient features of the fan are printed on the main section. The backside cover is also a flap over design. It has highlights of the technology behind these fans in 7 different languages. Major specifications are printed on the left side along with the warranty information. The left side has the model of the fan printed on the top with info labels on the lower side. The right side has model of the fan on the top with diagram of the fan under it. The top side has an opening cover which is in dark brown background. Noctua brand name and logo are printed over it in the middle. The fans are designed in Austria. The front side’s undercover has P/Q curve explained by the Noctua on the left side. The right side gives you a sneak peek of the fan and the accessory. The contents of the package are printed on the top. The backside undercover has salient features of the fan printed on both sides.

[Best_Wordpress_Gallery id=”8″ gal_title=”Noctua NF-A12x25 FLX”]

There is a transparent container inside the main box. It has two sections. The main section has the fan and an NA-AV2 mounting. The lower section has a plethora of accessories in it. The contents are:

[Best_Wordpress_Gallery id=”10″ gal_title=”Noctua NF-A12x25 FLX1″]

Design

Noctua NF-A12x25 is a new generation of premium fans from the premium brand. These fans are taking over their ever-popular NF-F12 and NF-S12A fans. Noctua is known as a leader in Noise-to-Performance ratio category and rightly so. Their designs are well researched and they deliver the best performance. The new generation of fans took them some 4.5 sweet years into the making. Why is that so, Noctua? Noctua has addressed multiple design aspects and is trying to re-invent the wheel. We will highlight some of the major aspects that took them that long but first let’s take a look at the specifications of the FLX fan.

The size of these fans is 120x120x25mm which is a standard size for 120mm fans. The maximum rated speed is 2000 RPM ±10%. Maximum speed using L.N.A is 1700 RPM ±10% and it is 1350 RPM ±10% with U.L.N.A. The airflow is rated at 60.13 CFM approximately. It is 49.77 CFM using L.N.A and 37.99 CFM using U.L.N.A. The sound level is rated 22.6 dB(A). It is 18.8 dB(A) with L.N.A and 14.2 dB(A) with the U.L.N.A. Static pressure is rated at 2.34 mmH₂O. It is 1.65 mmH₂O with L.N.A and 1.05 mmH₂O using U.L.N.A. The maximum input power is 1.68W with 0.14A maximum input current at 12VDC. The fans are using SSO2 bearings with MTTF ˃ 150000 hours.

[Best_Wordpress_Gallery id=”12″ gal_title=”Noctua NF-A12x25 FLX2″]

egular axial fans have their impellers made of PBT, ABS etc material. Over an extended period of time, due to centrifugal forces acting on the impellers widens the impellers a bit like 0.2mm or so. This phenomena is called impeller creep. Either there needs to be a gap enough for the impellers to widen and still not make contact with the fan’s frame or fan will simply start malfunctioning as there is not enough gap between the frame and the impeller. Leaving gap for the impeller would create further issues like back pressure from the impedance surface would create resonance and vibration that would contribute towards the acoustical noise and air leakage due to widened gap. This phenomena occurs due to the material of the impeller in part. Noctua has been searching for the material that could eliminate the impeller creep.

In doing so, they developed Sterrox from Liquid-Crystal Polymer (LCP). LCP is well known for the Kevlar which is used in the body armor in military applications. The LCP has much better dimensional stability and less creep as compared to the other materials like ABS, PBT, PC etc. Sterrox means rugged, firm, hard, solid which shows its true nature. Its extreme tensile strength, exceptionally low thermal expansion coefficient, high environmental inertia and excellent dimensional stability have made it possible to reduce impeller creep phenomena to levels that were previously unthinkable with PBT- or PA-based impellers.

This has enabled the Noctua to keep the distance between the impeller and the frame to be of mere 0.5mm which is a remarkable achievement. Sterrox also helped in reducing the vibration from the blades due to its exceptional chemical properties and molecular structure. In order for these challenges to be met, Noctua has taken several different measures that, from a manufacturing point of view, make the NF-A12x25 the most advanced and most elaborate Noctua fan to date.

Firstly, the centrepiece of the NF-A12x25’s motor hub is made entirely from steel in order to reinforce the outer plastic structure. At the same time, the axle mount has been reinforced with an additional brass piece in order to stiffen the joint between axis and impeller. In combination, both measures assure reduced tolerances and increased stability in the critical hub area. The NF-A12x25 impeller features suction side Flow Acceleration Channels. By speeding up the airflow at the crucial outer blade regions, this measure reduces suction side flow separation and thus leads to better efficiency and lower vortex noise.

Above was the core of the new generation of the fans from the Noctua. They are further supplemented by using the Noctua’s AAO (Advanced Acoustic Optimisation) frames that feature integrated anti-vibration pads as well as Noctua’s proprietary Stepped Inlet Design and Inner Surface Microstructures, both of which further refine the fan’s performance/noise efficiency. The stepped inlet design can be elaborately seen on the front side of the fan on the inner sides though there are fewer steps as compared to the ones on NF-F12. The fans have 8 anti-vibration pads on the mounting corners. These pads are removable to make the fans compatible with the Chromax series of the anti-vibration pads. The inner-microstructures can be seen from the backside of the fan in the form of vertical lines that are grooved on the inner frame. There is a 105mm distance between any two mounting holes. In addition, Noctua has bundled Anti-Vibration Gasket designed particularly for the water cooling radiators. These will form a perfect seal between the fan and radiator to avoid air leakage. In order to install this gasket, you would have to remove the already installed anti-vibration pads.

The NF-A12x25 features the further optimized second generation of Noctua’s renowned, time-tested SSO bearing. With SSO2, the rear magnet is placed closer to the axis to provide even better stabilization, precision, and durability. This is further enhanced by a CNC milled bearing shell made entirely from brass. The latest version of Noctua’s advanced Smooth Commutation Drive system ensures superb running smoothness by eliminating torque variations and switching noises. This makes the fan remarkably quiet even at very close distances.

The term FLX stands for Flexible. Noctua has given the user a total control over the speed of the fan using bundled Low Noise Adapter and Ultra Low Noise Adapter. Even, with the current generation of the fans, the primary focus of the Noctua is on the better sound level yet enhanced performance levels. Using L.N.A the fan would run at rated 1700 RPM ±10% and using U.L.N.A, the fan would run at 1350 RPM ±10%. The fan was literally inaudible on these speeds and one would have to bring their ears closer to the fan to hear them. The fan’s cable is short measuring 205mm. This is a good move by Noctua. Should a user need more length, they have included the 300mm extension cable. There is a 3:4 pin adapter in case you would want to power the fan directly from the PSU. We have tested the fan using the fan header by converting its regulation type to DC and fan responded perfectly to the change the fan speeds.

The fan 9 blades which have much less depth as compared to the pressure optimized fans. The diameter of the motor hub is quite large measuring 50mm. The fan feels quite heavy when in hand, this is due to the steel made motor hub which is further reinforced with brass made an axial mount. There is no sticker on the motor hub. Noctua brand name and logo are printed on one side of the frame. There are two arrows indicating the airflow direction and blades movement direction. The cable is sleeved. The backside has 4-arms assembly holding and securing the hub with the frame. The frame is made of the plastic. There is a sticker pasted on the backside of the hub. The upper portion has Noctua brand name and logo printed on it. The lower portion has the model of the fan and its power ratings.

With NF-A12x25 series of fans, Noctua is trying to achieve a single solution of two situations. People are most of the time concerned with the high static pressure fan or the high airflow fan depending on the situation is. They have shown P/Q graph where Y-Axis has Static Pressure rating and X-Axis has Airflow rating. The middle area is the one that is critical. NF-A12x25 has much better performance in this area. Not only that but it is reaching a high level of static pressure and high level of airflow. Thus Noctua is giving a two in one solution in the new generation fans.

Testing

We will be testing the unrestricted airflow of the Noctua NF-A12x25 FLX at various speed regulations using the Perfect Prime WD9819 Anemometer. To regulate the speed of the fan for this testing, we will use Reeven Polariz RFC-04 fan controller.

Airflow

Noctua is using the m³/h unit for the airflow. We are using the CFM unit. 1 m³/h is roughly equivalent to 0.589 CFM. The airflow rating for NF-A12x25 FLX is 60.13 CFM. In our unrestricted testing, the NF-A12x25 FLX version reaches 64.2 CFM validating the rated airflow value.

Speed Range

The speed range was tested at various voltage points starting from 5V going up to 12V. The NF-A12x25 FLX reaches 2020 RPM validating its rated speed. For comparison, the PWM range of the NF-F12 is also included in the graph.

Thermal Testing

Thermal performance of the fan was tested on this test bench:

The NF-A12x25 FLX was tested at 1350 RPM, 1700 RPM and 2000 RPM for which supplied Low Noise Adapter and Ultra Low Noise Adapter cables were used. Asus RealBench v1.44 was used to stress test the CPU. RealTemp was used to monitor the temperatures. First, the stress test was run on the stock clocks of 3.6GHz at 1.14V VCore. XMP was loaded all the times. Reported temps are delta ones which are calculated by subtracting the average of each core’s maximum temps from the ambient temp. Next, the Chip is overclocked to 4.3GHz at 1.350V VCore. XMP is loaded as well. Stress test is run again using the same methodology as described above and delta temps are noted.

The Noctua NF-F12 are PWM fans rated 1500 at RPM, with airflow of 55 CFM, an acoustical noise of 22.4 dB(A), and static pressure of 2.61mmH₂O. We are giving specification overview of the NF-F12 as this is the reference fan on our test bench.

Let’s take a look at the thermal performance results.

On 3.6GHz, at 100%, the NF-F12 was doing 28.67°C. At 1350 RPM the NF-A12x25 FLX was doing 29.83°C which is -1.16°C delta. At 1700 RPM, the NF-A12x25 was doing 28.01°C which is a delta of 0.66°C. At full speed, the NF-A12x25 FLX was doing 25.48°C which is a lead by the margin of 3.19°C.

On 4.3GHz, at 100%, the NF-F12 was doing 47.98°C. At 1350 RPM the NF-A12x25 FLX was doing 49.1°C which is -1.12°C delta. At 1700 RPM, the NF-A12x25 was doing 46.23°C which is a delta of 1.57°C. At full speed, the NF-A12x25 FLX was doing 45.16°C which is a lead by the margin of 2.82°C.

The acoustical performance of the new generation of fans is in close proximity with the NF-F12. They were near to silent and even at full speed their audible sound was not teasing. This is a great achievement by Noctua.

Conclusion

We get to test the Noctua’s new generation of fan from NF-A12x25 series. After a wait of like 4.5 years, Noctua has finally released their new generation of fans. They have definitely tried to re-invent the wheel here. The underlying technologies in the new generation of fans are worth mentioning as Noctua seems to be setting a new trend here. While the industry is primarily focused on the RGB LED Lighting on the fans, Noctua is untouched with this trend and rightfully so as Noctua is known for bringing out the top notch, well thought out and researched cooling solutions in their typical coloring. They are sticking with it this time as well. We have reviewed the NF-A12x25 FLX version where FLX stands for the Flexible. Noctua has enabled the users to select between three speed settings by using the supplied Low Noise Adapter (L.N.A) and Ultra Low Noise Adapter (U.L.N.A) with speed of 1700 RPM ±10% with the L.N.A and 1350 RPM ± 10% in addition to the full rated speed of 2000 RPM ±10%. Here is a quick rundown of the specifications. The size of these fans is 120x120x25mm which is a standard size for 120mm fans. The maximum rated speed is 2000 RPM ±10%. Maximum speed using L.N.A is 1700 RPM ±10% and it is 1350 RPM ±10% with U.L.N.A. The airflow is rated at 60.13 CFM approximately. It is 49.77 CFM using L.N.A and 37.99 CFM using U.L.N.A. The sound level is rated 22.6 dB(A). It is 18.8 dB(A) with L.N.A and 14.2 dB(A) with the U.L.N.A. Static pressure is rated at 2.34 mmH₂O. It is 1.65 mmH₂O with L.N.A and 1.05 mmH₂O using U.L.N.A. The maximum input power is 1.68W with 0.14A maximum input current at 12VDC. The fans are using SSO2 bearings with MTTF ˃ 150000 hours.

This new generation is utilizing the new in-house developed Liquid-Crystal Polymer (LCP) based material called Sterrox that has enabled the Noctua to reduce Impeller Creep and to keep the gap between the impeller and frame to be 0.5mm which is a huge milestone for the Noctua. This design helps in reducing back pressure that caused resonance and vibration as well to stop the air leaks along the blades’ tips. To strengthen the design the motor hub is made of the steel and further reinforced by brass structure along the axial mount. This is combined with their Advanced Acoustics Optimization by using the anti-vibration pads on the mounting corners, stepped inlet design around the border of the front side of the fans, and inner microstructures. The trailing edges have Flow Acceleration Channels. By speeding up the airflow at the crucial outer blade regions, this measure reduces suction side flow separation and thus leads to better efficiency and lower vortex noise. These fans include a plethora of accessories including the NA-AV2 anti-vibration mount, anti-vibration gasket for water cooling radiators, 4x screws, Low Noise Adapter, Ultra Low Noise Adapter, 30cm extension cable, and 3:4 pin adapter. These fans come with Noctua’s 6 years warranty.

The Noctua NF-A12x25 FLX is rated at $29.90 at the time of the review. A bit expensive ordeal but given the number of accessories and performance level, they are worth it. In our testing, this fan has performed exceptionally well by delivering the enhanced thermal performance yet at the same sound level that the NF-F12 is at which is truly a technological masterpiece. These fans are available in 3 versions, PWM with automatic speed regulation, FLX with 3-speed settings and ULN with Ultra Low Noise operations in focus.

Based on the exceptional performance and low noise levels, we are awarding these fans our Must Have Award. If you are in the market looking for the fans that can not only be used for high impedance situations as well as adequate enough for your airflow requirements, look no further as Noctua has provided a complete solution in a single fan under their NF-A12x25.