Featuring advanced aerodynamic design measures such as Flow Acceleration Channels and Noctua’s AAO frame, the NF-A6x25 FLX is a highly optimised, premium quality quiet fan in 60x25mm size. Smooth Commutation Drive technology and Noctua’s reference class SSO2 bearings guarantee superb running smoothness and excellent long-term stability. Topped off with modular cabling, Low-Noise Adaptors and 6 years manufacturer’s warranty, the NF-A6x25 is a premium choice for the highest demands.
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.
Smooth Commutation Drive 2

Smooth Commutation Drive 2

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 NF-A6x25 remarkably quiet even at very close distances.
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.
3 speed settings for full flexibility

3 speed settings for full flexibility

Providing 3000, 2400 and 1600 rpm speed settings via the supplied Low-Noise and Ultra-Low-Noise Adapters, the NF-A6x25 FLX (Flexibility) can be fine-tuned for superior airflow or maximum quietness.
Extensive cabling options

Extensive cabling options

The fan's short 20cm primary cable minimises cable clutter in typical applications while the supplied 30cm extension provides extended reach when necessary. Both cables are fully sleeved and the supplied 3:4 pin adaptor allows the connection of the fan directly to the power supply.
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 FLX
FAN Specification
60x60x25 mm
Mounting hole spacing
50x50 mm
Blade Geometry
Rotational Speed (+/- 10%)
3000 RPM
Rotational Speed with L.N.A. (+/- 10%)
2400 RPM
Rotational Speed with U.L.N.A. (+/- 10%)
1600 RPM
Acoustical Noise
19,3 dB(A)
Acoustical Noise with L.N.A.
14,5 dB(A)
Acoustical Noise with U.L.N.A.
8,2 dB(A)
Static Pressure
2,18 mm H₂O
Static Pressure with L.N.A.
1,41 mm H₂O
Static Pressure with U.L.N.A.
0,61 mm H₂O
Max. Input Power
1,44 W
Max. Input Current
0,12 A
12 V
> 150.000 h
Scope of Delivery
  • Low-Noise Adapter (L.N.A.)
  • Ultra-Low-Noise Adapter (U.L.N.A.)
  • 3:4-Pin Adaptor
  • 30cm Extension Cable
  • 4 Vibration-Compensators
  • 4 Fan Screws
6 years
NF-A6x25 FLX
A-Series fans
09.02.2015 // QWERTYmag.it

NF-A6x25 FLX Review

In questa recensione ci siamo realmente resi conto di quanto Noctua sia attenta ai dettagli e alla cura dei propri prodotti anche in delle “semplici” ventole che poi, in questo caso specifico, semplici non sono visto l’elevata cura nella produzione e nelle tecnologie adottate. Ci ha stupito moltissimo il fatto di ritrovare tutte le tecnologie citate nell’introduzione anche nelle ventole di dimensione ridotta come le NF-A4. Siamo decisamente soddisfatti sia dalle prestazioni in termini di efficienza/rumore, sia dal bundle che dai prezzi decisamente in linea con quelli di altri produttori ma assolutamente superiori in termini di caratteristiche e prestazioni. Attribuiamo a tutta la NF-A Series il premio Gold Award per l’innovazione tecnologica e la cura dei particolari che L’azienda ha dimostrato in questa serie di ventole super-efficienti.
Test verdict: "Ventole per ogni tipo di esigenza. Noctua con la serie NF-A ha pensato proprio a tutti e a tutto proponendo prodotti di altissima qualità e tecnologia mantenendo un ottimo rapporto qualità/prezzo. Decisamente apprezzata la cura dei dettagli e del bundle che rendoni queste ventole il TOP DI GAMMA sul mercato." (Davide Torno, QWERTYmag.it)
17.01.2013 // PC Ekspert

NF-A6x25 FLX Review

Cijene manjih (A4x10/A6x25/A9x14 – 12,90/14,90/16,90€), kao i većih 140mm modela (21,90€) su uglavnom u skladu s dosadašnjom politikom Noctua proizvoda, koja se i dalje bazira na principu – kvaliteta prije svega, uz odgovarajuću cijenu. Nakon svega viđenog, zaista im ne možemo puno zamjeriti na tome, s obzirom na sve prednosti njihovih proizvoda iz nove A-serije za koje imamo gotovo isključivo riječi hvale.
Test verdict: "Noctua nam je ovom prilikom priredila mnoga iznenađenja po pitanju novih proizvoda raznih veličina i namjena. Od minijaturnog 40mm A4x10 modela, preko A6x25 i A9x14, pa sve do 140mm inačica, svaki od testiranih ventilatora odaje onu poznatu Noctua kvalitetu i uglađenost u radu uz visoku funkcionalnost i bogatu dodatnu opremu. Za svakoga ponešto, bi možda bio najslikovitiji opis nove A-serije ventilatora, a što se nas osobno tiče, itekako bismo voljeli vidjeti par 140mm ULN modela i u našem testnom računalu. Za korisnike koji zahtijevaju veliku efikasnost i relativno umjeren nivo buke, tu su naravno A14 FLX i A15 PWM modeli, koji svojom fleksibilnošću, elegantnim radom ali i visokom kvalitetnom izrade itekako zaslužuju našu preporuku." (Domagoj Hodak, PC Ekspert)
22.11.2012 // DragonSteelMods.com

NF-A6x25 FLX Review

Once I got it all installed I powered it on and it didn’t work, at least not at first, the fan apparently comes on when the blu-ray player gets warm enough. (I already knew this actually as I made sure by testing the original fan first) The fan worked perfectly as the original did. The Noctua fan is much quieter than the original fan, which is what you want for something that’s in your home theater. Who wants to hear a fan whirring while they’re watching a movie right? I know I don’t.
Test verdict: "The installation of this type and size of fan will vary on your uses or needs of course, but for any purpose I think it will work just fine. Noctua is known for quality products and their new line of fans certainly keep up with that tradition. My installation was just one option of countless ones I’m sure, but for me it works very well at keeping things cool and being quiet at the same time. Noctua has shown that no matter what your uses, they have the right fan for you." (Kristofer Brozio, DragonSteelMods.com)
20.11.2012 // HWBox.gr

NF-A6x25 FLX Review

O... μεσαίος της παρέας ξύπνησε αναμνήσεις. Έχουν περάσει αρκετά χρόνια από τότε που χρειαζόμασταν να βάζουμε αρκετούς ανεμιστήρες στα τυπικά τσίγκινα μπεζ κουτιά που χρησιμοποιούσαμε για το μηχάνημά μας, και από τις λιγοστές θέσεις που περιελάμβαναν, σίγουρα θα υπήρχε κάποια που ήταν μέγιστο 80mm αλλά μπορούσε να φιλοξενήσει και 60άρηδες, οι οποίοι πέρα από δυσεύρετοι, ήταν και θορυβώδεις. Να όμως που εν έτη 2012 συνεχίζουν και υπάρχουν, και μάλιστα υπό το όνομα της Noctua! Ο ανεμιστήρας διαθέτει μια διαφορετική σχεδίαση, καθώς το πλάτος του έλικα όσο και το συνολικό πλάτος του ανεμιστήρα είναι υψηλού προφίλ και ανέρχεται στα 25mm, παρόμοιο δηλαδή με έναν τυπικό ανεμιστήρα. Με την αρκετά επιτυχημένη (επαν-)είσοδο των desktop cases για mITX form factor, τα οποία έχουν ύψος που μετά δυσκολίας μπορεί να χωρέσει κάποιον 80mm ανεμιστήρα, ίσως και να βρήκατε την -ήσυχη- λύση που αναζητούσατε! Στις τυπικές προδιαγραφές του ανεμιστήρα, μπορεί να παρέχει 50,5 m^3/h στις 2200 RPM(max) και όλα αυτά με ονομαστικό θόρυβο 19,3 dB.
Test verdict: "Δυστυχώς, το τίμημα για κάτι τέτοιους ανεμιστήρες είναι αρκετά υψηλό, αν και είναι δεδομένη η υψηλή ποιότητά τους και η πληθώρα αξεσουάρ με τα οποία συνοδεύονται." (Vasilis Galiouras, HWBox.gr)
14.11.2012 // El Chapuzas Informático

NF-A6x25 FLX Review

Hemos probado los tres ventiladores y gratamente nos ha sorprendido su bajo nivel de ruido generado. El modelo de A4x10 es el único mínimamente más audible, pero por sus altas revoluciones es normal. Los modelos de 40 y 60 mm son perfectos para sistemas embebidos que requieren un ventilador para la extracción de aire, así como para los amantes del modding que deseen refrigerar zonas de su PC de menor superficie. El modelo de 90 mm es ideal para equipos HTPC con disipadores de perfil bajo, que lo verán aún más reducido al cambiar los habituales ventiladores de 25 mm de grosor por este de 14 mm.
Test verdict: "Los ventiladores Noctua Serie-A ofrecen en formato compacto el rendimiento esperado por un ventilador de esta prestigiosa marca: gran flujo de aire a un mínimo nivel sonoro. Su uso está limitado a necesidades concretas, por lo que gran parte de los usuarios no tendrán necesidad de ellos. Sin embargo, los que requieran productos de estas dimensiones agradecerán en gran medida el lanzamiento de estos ventiladores tan eficientes por parte de Noctua." (Iván Martínez, El Chapuzas Informático)
28.10.2012 // PCkoloji.com

NF-A6x25 FLX Review

3-pin girişle beslenen sabit hız fan 3000 devire çıkıyor ama inanılmaz sessiz ve sadece 19.3 dBA gürültü yapıyor. Hava akımı 29.2 m³/h gibi etkileyici bir değer. 92 mm modele göre çok daha ufak olmasına rağmen aynı gürültüyle yüzde 60′ı kadar hava basabiliyor. LNA hız kesici ile hız 2400 devire, gürültü 14.5 dBA’e ve akım 23.5 m³/h değerine iniyor. Bu durumda sesini duymak çok çok zor ama hava akımı çok başarılı.
Test verdict: "ULNA filtre ile hız 1600 devir, gürültü 8.2 dBA ve akım 16.7 m³/h. Akım düşük olsa da sesini duymak için 2 cm mesafeden kulak dayamak gerekiyor! En yüksek devirde 1.44 Watt güç tüketen ve 12V ile beslenen fanın kullanım ömrü en az 150 bin saat. Bu modelde de darbe emici kenar kauçukları var." (Görkem Yildirimy, PCkoloji.com)
22.10.2012 // HD Technology

NF-A6x25 FLX Review

Le ventole Noctua della nuova serie A, sono state veramente all’altezza delle nostre aspettative, qualità impeccabile ed una longevità eccezionale. Gli appassionati potranno utilizzare queste ventole per una durata di oltre 150.000 con una garanzia sul prodotto di ben 6 anni. Come tutte le fan delle varie serie, sono curate minimamente sotto ogni punto di vista.
Test verdict: "Con questa recensione, non possiamo far a meno di consigliarvi queste ventole per chi utilizza un HTPC." (Victor Italiano, HD Technology)
11.10.2012 // Hardware - HDblog

NF-A6x25 FLX Review

Dall’immagine si evince che, anche se siamo davanti a delle ventole molto piccole, la potenzialità che presentano è notevole anche rispetto alla sorella più grande da 92 mm, facendo registrare la stessa temperatura dell’hard disk utilizzando il modello A6x25 e, la ventola più piccola soltanto un grado di differenza rispetto alle sorelle più grandi. Segnaliamo infine la poca rumorosità di tutti e tre i modelli, confermando di fatto le specifiche proposte dall’azienda.
Test verdict: "Come da copione, anche con queste nuove ventole Noctua non ci ha delusi, proponendo prodotti che anche se di piccole dimensioni svolgono bene il proprio lavoro sia per prestazioni che la qualità; tutti e tre i modelli sono ideali per chi cerca prestazioni ottimali per il proprio sistema senza tralasciare la rumorosità." (Michele Bruno, Hardware - HDblog)
08.11.2015 // AndroidPC.es

NF-A6x25 FLX Review

Después de probar los modelos NF-A6x25 PWM, NF-A6x25 FLX, NF-A4x10 FLX y NF-A4x10 5V nos dan ganas de dejar un ventilador en nuestras placas pasivas, pero preferimos no hacerlo, como ya sabéis nos gustan los sistemas pasivos. Ciertamente es estos productos pueden ofrecen una mejora térmica en nuestros dispositivos si vamos a exprimirlos y además no nos molestan con ruidos. Si tenemos algún modelo pasivo con problemas térmicos añadirle un pequeño ventilador bien dimensionado siempre es una solución, sobretodo si tienen la calidad de estos modelos.
Test verdict: "Los recomendamos sin ninguna duda para quien quiera mejorar el rendimiento de su miniPC o AndroidPC con problemas térmicos." (Joaquin Prida Trujillo, AndroidPC.es)
03.11.2014 // Conseil Config

NF-A6x25 FLX Review

Malgré la taille qui présageait des nuisances sonores horribles comme nous avons tous l'habitude d'entendre venant de ventilateurs comme ceux-ci, et bien il n'en est rien! Le ventilateur qui me faisait le plus peur était le tout petit Ax410, un ventilateur de 4cm qui, tournant à 4500 RPM, me donnait mal aux oreilles avant même de le brancher, mais au final il se révèle être extrêmement silencieux, du très bon pour Noctua qui pourra enfin vous réconcilier avec vos appareils utilisant des ventilateurs de cette taille. Le A6x25 est le plus silencieux du lot, il n'y a aucun bruit parasite audible et il saura se faire discret même au maximum. Le A9x14, qui n'est autre qu'un ventilateur 92 mm au format "low profile" est un modèle qui est très intéressant si vous êtes en manque de place dans vote HTPC (ou tout autre boitier avec peu de place), il a une grande plage d'utilisation et saura se faire très discret, à noter qu'il émet un léger son aigu à plein régime.
Test verdict: "Que dire de cette série un peu spéciale de chez Noctua? Au départ un peu sceptique quant au bruit que génèrent généralement ces types de ventilateurs il faut avoué que j'ai été agréablement surpris. [...] si vous cherchez à remplacer un ventilateur criard (par exemple dans un switch, ou un NAS etc..) par un silencieux vous avez trouvé ce qu'il vous faut!" (Christian Marchini, Conseil Config)

Installation Manual (PDF)

Information Sheet (PDF)

Can I run Noctua 3-pin fans on 4-pin PWM connectors and use my mainboard’s automatic fan controller?

You can simply connect our fan's 3-pin connector to the 4-pin PWM sockets of today's mainboards so that the fourth pin that transmits the PWM signal is left blank (due to the shape of the connector, there's no danger of reversing polarity). Some mainboards (e.g. current Gigabyte models) are capable of controlling fans not only via PWM, but also by adjusting the supplied voltage. In some cases, this may require you to change BIOS options like "Fan Control Mode" from "PWM" to "Voltage" or "Analog". Please consult your mainboard's manual in this regard. However, some mainboards use an "auto" setting by default that automatically chooses PWM or voltage based regulation according to the connected fan. Automatically controlling the fan speed may not possible on mainboards that pulse the power rather than lowering the fan voltage.


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.

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 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.

What pin configuration do Noctua 12V fans use?

All Noctua fans feature the standard pin-configurations set out in the Intel and AMD specifications. These standard pin-configurations are used on most mainboards and fan controllers today:

pin configuration

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:


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.

My Noctua 3-pin fan starts to spin when the PC boots but then stops, what is wrong?

Many mainboards are able to automatically regulate the fan speed of 3-pin fan via voltage based measures. However, due to limitations of this method it may occur that the mainboard reduces the voltage so much that the fan stops. To resolve the issue, you can:

  1. Choose a higher fan speed profile in the BIOS (e.g. „normal“ instead of „silent“, etc.) or deactivate automatic fan speed control and use a Low-Noise Adaptor instead.
  2. Use the mainboard‘s fan speed control software or 3rd party tools like Speedfan to regulate the fan speed. Unlike BIOS based fan speed control, the supplied software usually checks whether the fan has stopped and increases voltage accordingly or at least offer more options to set up the fan properly.

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!


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 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.

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.

Do you have a question concerning one of our products? Please use this form to pose a question!