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Featuring advanced aerodynamic design measures such as Flow Acceleration Channels and an AAO frame, the NF-A6x25 5V PWM is a PWM-enabled 5V variant of Noctua’s highly optimised, premium-quality quiet 60x25mm fan. The custom-designed NE-FD1 PWM IC that integrates Smooth Commutation Drive technology and Noctua’s reference-class SSO2 bearing guarantee superb running smoothness and excellent long-term stability. Topped off with modular cabling, the OmniJoin™ Adaptor Set and a 6-year manufacturer’s warranty, the NF-A6x25 5V PWM is a premium choice for demanding 5V applications that require PWM control.
Being a 5V fan, the NF-A6x25 5V PWM cannot be run at 12V and will be damaged when used with typical 12V power sources such as PC motherboard fan headers.
Details
5V PWM version

5V PWM version

Many devices, such as network or storage solutions, use 5 volt 60mm fans with PWM speed control. With the same operating voltage, PWM support and the included OmniJoin™ adaptor set that makes it compatible with proprietary fan headers, the NF-A6x25 5V PWM is ideal for replacing noisy or broken 5V 60mm fans with PWM.
Polarity protection

Polarity protection

As many devices using 5V fans feature proprietary connectors and documentation of the pin alignment may not be available, the fan features an integrated diode for polarity protection. This way, you're on the safe side if you accidentally connect it with reverse polarity.
Reduced Motor Hub Size

Reduced Motor Hub Size

Thanks to its streamlined, compact motor design, the NF-A6x25's motor hub is smaller than with conventional 6cm fans. This allows for more blade surface area and thus contributes to the NF-A6x25's superior airflow and pressure performance.
Flow Acceleration Channels

Flow Acceleration Channels

The NF-A6x25 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.
AAO Frame

AAO Frame

Noctua's AAO (Advanced Acoustic Optimisation) frames 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.
Stepped Inlet Design

Stepped Inlet Design

Noctua's Stepped Inlet Design adds turbulence to the influx in order to facilitate the transition from laminar flow to turbulent flow, which reduces tonal intake noise, improves flow attachment and increases suction capacity, especially in space-restricted environments.
Inner Surface Microstructures

Inner Surface Microstructures

With the tips of the fan blades ploughing through the boundary layer created by the Inner Surface Microstructures, flow separation from the suction side of the blades is significantly suppressed, which results in reduced blade passing noise and improved airflow and pressure efficiency.
Integrated Anti-Vibration Pads

Integrated Anti-Vibration Pads

Integrated Anti-Vibration Pads made from extra-soft silicone minimise the transmission of minute vibrations while maintaining full compatibility with all standard mounting systems and fan clips used on heatsinks.
Custom-designed PWM IC with SCD

Custom-designed PWM IC with SCD

Supporting fully automatic PWM speed control, the fan uses Noctua's custom-designed NE-FD3 5V PWM IC that integrates Smooth Commutation Drive (SCD) technology. By providing smoother torque impulses, SCD suppresses PWM switching noises and thus makes the fan quieter at low speeds.
SSO2 bearing

SSO2 bearing

The NF-A6x25 features the further optimised 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 stabilisation, precision and durability.
OmniJoin™ Adaptor Set

OmniJoin™ Adaptor Set

Many devices featuring 60mm fans use proprietary fan headers, so the NF-A6x25 5V PWM comes with Noctua’s OmniJoin Adaptor Set. Just cut the original fan’s cable, fix it to the adaptor using the supplied 3M Scotchlok™ connectors and you can plug the NF-A6x25 5V PWM to proprietary fan headers!
6-year manufacturer’s warranty

6-year manufacturer’s warranty

Noctua fans are renowned for their impeccable quality and outstanding longevity. Like all Noctua fans, the NF-A6x25 features an MTTF of more than 150.000 hours rating and comes with a full 6-year manufacturer's warranty.
NF-A6x25 5V PWM
General
Notes and warnings
Being a 5V fan, the NF-A6x25 5V PWM cannot be run at 12V and will be damaged when used with typical 12V power sources such as PC motherboard fan headers.
FAN Specification
Size
60x60x25 mm
Mounting hole spacing
50x50 mm
Connector
4-Pin PWM
Bearing
Blade Geometry
Rotational Speed (+/- 10%)
3000 RPM
Min. Rotational Speed (PWM, +/-20%)
650 RPM
Acoustical Noise
19,3 dB(A)
Static Pressure
2,18 mm H₂O
Max. Input Power
1,3 W
Max. Input Current
0,26 A
Voltage
5 V
MTTF
> 150.000 h
Scope of Delivery
Warranty
6 years
NF-A6x25 5V PWM
A-Series fans
03.08.2016 // GreenTechReviews.ru
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NF-A6x25 5V PWM Review

Обязательно отметим, что при довольно небольшом проигрыше вентилятору от Delta, уровень шума от новинок Noctua разительно отличается — их очень слабо слышно, в то время как детище Delta чрезвычайно громкое.
Test verdict: "Новый вентилятор Noctua NF-A6x25 5V PWM продемонстрировал отличную эффективность при сниженном энергопотреблении и низком уровне шума, обладая ещё и возможностью снижать скорость работы. Команда из Австрии не только применила все свои предыдущие наработки, но и усовершенствовала вентилятор в плане питания — ему достаточно лишь 5 В!" Владимир Солонин, GreenTechReviews.ru)
27.07.2016 // Overclockers.com
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NF-A6x25 5V PWM Review

The NF-A6x25 5V fans came with a variety of features that you normally see only on full-sized. Noctua did not stint with these, despite their diminutive dimensions. The frame “micro-structures” in particular were cute. With these little things in your hands, you have to marvel at how they made things like stepped inlets and cushioned screw holes on frames this small. The fans also come with a variety of accessories that will allow you to adapt them to the various situations you might meet.
Test verdict: "These are cute little fans. You will probably would not have found a place for them in your computer system a few years ago, but with small form factors coming on you may need something this small. Certainly some pre-made computers from major manufacturers feature fans this small in their PSU’s. But network equipment may use a cooling fan of this size. The fans that come with the equipment may fail. Or they may be very noisy. You may wish to replace the fans that came with the equipment with quiet fans. These are quiet fans. (Ed Humes, overclockers.com)

Installation Manual (PDF)

Information Sheet (PDF)

Can I paint my Noctua fan in order to change its color?

Since even small variations in the layer of paint can lead to an imbalance of the impeller, resulting in vibrations, higher noise levels, increased stress on the bearing and thus reduced lifespan, we do not recommend painting the fan. Please note that for the reasons stated above, painting the fan will void your warranty.

How can I find out the direction of airflow and sense of rotation?

When looking at the fan so that the circular sticker with the Noctua logo is facing you, the direction of airflow is towards you and the sense of rotation is clockwise:

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You specify airflow in m³/h, how can I convert to CFM?

In accordance to the International System of Units (SI system), Noctua specifies volumetric flow rate (airflow) using the SI unit of cubic metres per hour (m³/h). The SI unit can easily be converted to cubic feet per minute (CFM): One m³/h is ~0.589 CFM and one CFM is ~1.699 m³/h. For convenient conversion, online tools such as www.convertunits.com can be used.

Can I register my Noctua product?

Striving for excellence in both product and service quality, we believe that warranty and support should not depend on the customers willingness to provide his data throughout a registration process. We therefore do not offer the possibility to register Noctua products and provide the same 6-year manufacturer’s warranty and the same excellent level of support for all products.

What pin configuration do Noctua 5V fans use?

The pin configuration of Noctua 5V fans is identical to 12V fans:

5v pin configuration

I get a CPU fan error despite the fan is running!

Some mainboards display a CPU fan error when the fan speed falls below a certain threshold, e.g. 900rpm. If you want to run the fan below this speed (e.g. using the supplied U.L.N.A.), please adjust the threshold in the BIOS or disable CPU fan error warning.

How should I clean my Noctua fan?

Fans inside computer cases tend to accumulate dust over longer periods of usage. In order to maintain maximum performance, please clean your fans regularly using a duster, slightly moist tissue or canned air. Please be careful not to use too much force in order to prevent any damage to the fan. Please do not use a vacuum cleaner as this may apply excessive force to the fan and do not put the fan under running water as water residues inside the motor may lead to short circuits.
In order to ensure flawless operation over many years of usage, Noctua’s premium grade SSO bearings are fully sealed to prevent the entering of fine dust particles. Please note that the fan is not designed to be taken apart by the user. Removing the impeller from the frame will break the sealing of the bearing and results in a loss of warranty.

Can I disassemble my fan for cleaning (or other purposes, e.g. painting)?

In order to ensure flawless operation over many years of usage, all Noctua fans come with a premium grade SSO bearing, which is fully sealed to prevent the entering of fine dust particles. Please note that the fan is not designed to be taken apart by the user. Removing the impeller from the frame will break the sealing of the bearing and results in a loss of warranty.

It is thus recommended to clean your fans using a duster, slightly moist tissue or canned air. Please be careful not to use too much force in order to prevent any damage to the fan. Please don’t use a vacuum cleaner as this may apply excessive force to the fan.

Can I run 4-pin PWM fans on 3-pin fan headers?

PWM fans come with a 4-pin connectors for fully automatic speed control via your mainboard’s 4-pin PWM fan headers. Please note that 4-pin fans can also be connected to your mainboard’s 3-pin fan headers though. When connected to 3-pin fan headers, the fan will run at full speed (unless the mainboard supports voltage based speed control).

How can I check if my 4-pin fan header supports PWM?

Some mainboards feature 4-pin fan headers that actually don‘t use a PWM signal on Pin 4 to control the fan speed but rather reduce the voltage on Pin 2 (like a standard 3-pin fan header). As the fan speed at minimum voltage is usually higher than the speed at 20% PWM duty cycle, the fan can not reach as low minimum speeds under voltage control as under PWM control. Please refer to your mainboard manual to check whether or not your mainboard has 4-pin fan headers that control the fan speed by reducing voltage on Pin 2 rather than by changing the PWM duty cycle on Pin 4:

4 pin fan header types

Note that mainboard manufacturers use different terms to indicate that Pin 4 is not being used for PWM control (e.g. “+5V”, “VCC” or “NC”), but if one of these terms is used, you can be sure that the fan header does not support PWM. If Pin 4 is described as “Speed Control” or “PWM” or the like, you can be sure that the fan header supports PWM.

Unfortunately, the description of Pin 2 is not always a clear indication as some manufacturers use terms such as “Fan PWR” or “Power” for both types of fan headers. However, if Pin 2 is described as “Speed Control”, you can also be sure that the fan header does not support PWM based speed control. If Pin 2 is described as “+12V”, this is a clear indication that the fan header supports PWM.

Please also note that in some cases, the descriptions of the pin layouts in the mainboard manuals may not be correct and some models actually allow you to switch the fan headers from voltage control mode to PWM control mode in the BIOS even though the pin descriptions do not indicate PWM support. We thus recommend to look for these options in the BIOS before taking other measures. In case of doubt, please contact your mainboard manufacturer.


If your mainboard features other 4-pin fan headers that use PWM for speed control, you can run multiple fans from these headers using Y-split cables. Make sure not to exceed the specified maximum power draw of the fan headers (usually 10-12W) though.

Can I use Noctua fans in my system from Acer, Apple, Dell, HP, Lenovo or other major brands?

Noctua 12V fans comply with the established specifications for standard PC systems issued by Intel and AMD. Systems from Acer, Apple, Dell, HP, Lenovo or other major brands often deviate from these specifications e.g. by using proprietary fan headers, custom pin-alignments or pin-configurations, different methods of fan speed control, etc. This can lead to compatibility issues when using Noctua fans in systems from said brands. Some of these problems can be avoided with some technical knowledge, but especially BIOS related issues (e.g. errors or shutdowns due to low fan speed) can often not be resolved. As a result, Noctua does not officially support systems from Acer, Apple, Dell, HP, Lenovo or other major brands.

Can Noctua fans be used to replace noisy stock fans in NAS devices?

Noctua fans such as the 40, 60, 80 or 92mm NF-A series models are ideal for replacing noisy stock fans in NAS devices in order to make them quieter and thousands of users have managed to significantly reduce the noise levels of their NAS units this way. However, while it is easy and straightforward to replace the fans in some cases, it can be very difficult in others, so Noctua strongly recommends that users carefully research if it is possible to easily replace the fan(s) of their NAS device before purchasing a Noctua fan for this purpose. Some of the common issues that can occur when replacing NAS fans are:

  • Different pin assignment: Whereas Noctua fans use the standardised pin assignment for PC fans (see this FAQ for details), some NAS units use different assignments. For example, some devices have the power and GND or rpm and PWM pins swapped. Therefore please carefully verify that your NAS device uses the same pin assignment as standard fans. Experienced users may also change the pin assignment by cutting and resoldering the fan cables, but please note that this will void your Noctua manufacturer’s warranty.
  • Different pin functions: Noctua fans use the standardised pin functions for PC fans (see this FAQ for details); however, some NAS units use fans where certain pins serve a different function. For example, some devices use the RPM pin for “power good” signals. Therefore please carefully verify that your NAS device uses the same pin functions.
  • Firmware speed control: Some NAS devices demand a certain maximum or minimum fan speed. If the new fan doesn’t have the same or similar maximum or minimum speed, the device may display errors or even shut down.
  • Different starting voltage: Most NAS devices use voltage-based speed control. If the new fan has a higher starting voltage than the original fan, it may not start up right away. This may lead the NAS device to display errors or even shut down because it suspects a fan failure.
  • Different power draw: Some NAS devices monitor the fan’s power draw. If the new fan has a lower power consumption than the stock fan, the device might display errors or even shut down.

Please note that most NAS manufacturers don’t provide detailed documentation regarding fan compatibility and control, so users who want to replace the fans of their devices usually have to rely on “How to” guides, blog and forum posts or video tutorials. For example, there are excellent video tutorials available for changing the fans in popular Synology NAS models (DS416j, DS1515+ and DS1812+ in English, DS416/DS415/DS916/DS216/DS214 and DS1515+ in German). Please also note that fan compatibility and control can vary from model to model and even from revision to revision even if the devices stem from the same manufacturer. As a result, it is important to make sure that the information or guidelines you rely on when replacing your NAS fan are applicable to your specific model as well as your specific hardware and firmware revision.

Due to the possible issues listed above, Noctua recommends that only experienced users attempt to replace their NAS fans. Please note that since there are so many different NAS models and most of them lack documentation for aspects such as fan compatibility and control, Noctua customer support cannot assist you with compatibility issues when replacing NAS fans. Please contact your NAS manufacturer for any questions regarding aspects such as the device’s pin alignment or fan monitoring and control.

Can I use Low-Noise Adaptors with y-cables / multiple fans?

Yes, Low-Noise Adaptors (L.N.A.s) can be used with y-cables, but please make sure to use one L.N.A. per fan and to place the L.N.A.s between the y-cable and the fans as shown below. Never use one L.N.A. for two (or more fans) by placing it between the mainboard and the y-cable!

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Which Noctua fan or CPU cooler should I buy? How to choose the right model?

Not sure which Noctua product to buy? Our detailed buying guides for fans and CPU coolers help you to choose the model that works best for you.

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