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NF-A4x20 PWM 5V 5000RPM 40x20mm Quiet Cooling Fan €15,25
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(4 customer ratings / 1 review)
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Noctua NF-A4x20 PWM 5V 5000RPM 40x20mm Quiet Cooling Fan

After the success of Noctua’s NF-A4x10 40mm fans we are delighted to offer the 20mm wide version that offers increased static pressure performance.

Features

  1. 40 x 20mm quiet PC cooling fan, 5V version
  2. Supports fully automatic PWM speed control
  3. Feature packed
  4. Perfect for proprietary cooling
  5. From 5.5 CFM, 14.9 dBA at 5000 RPM

Featuring advanced aerodynamic design measures such as Flow Acceleration Channels and an AAO frame, the NF-A4x20 5V PWM is a PWM enabled 5V variant of Noctua’s highly optimised, premium quality quiet 40x20mm fan. The custom designed NE-FD3 PWM IC that integrates 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, the OmniJoin Adaptor Set and 6 years manufacturer’s warranty, the NF-A4x20 5V PWM is a premium choice for demanding 5V applications that require PWM control.

PLEASE NOTE: Being a 5V fan, the NF-A4x20 5V PWM cannot be run at 12V and will be damaged when used with typical 12V power sources such as PC motherboard fan headers.

40x20mm size

Compared to Noctua’s award-winning NF-A4x10, the NF-A4x20 is twice as thick, which allows for increased static pressure performance and makes the NF-A4x20 ideal for demanding applications with high flow resistance.

5V PWM version

Many devices such as network or storage solutions use 5 volt 40mm 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-A4x20 5V PWM is ideal for replacing noisy or broken 5V 40mm fans with PWM.

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.

Flow Acceleration Channels

The NF-A4x20 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

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

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

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 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.

SSO2 bearing

The NF-A4x20 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.

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.

Low-Noise Adaptor

The NF-A4x20 PWM is supplied with a (L.N.A.) that reduces the maximum fan speed from 5000 to 4400rpm. The L.N.A. can be used either to run the fan at a fixed speed of 4400rpm or to cap the maximum speed when using automatic PWM control.

OmniJoin adaptor set

Many devices featuring 40mm fans use proprietary fan headers, so the NF-A4x20 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-A4x20 to proprietary fan headers!

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 a 4-pin y-cable allows the connection of a second fan to the same PWM fan header for automatic control.

6-year manufacturer’s warranty

Noctua fans are renowned for their impeccable quality and outstanding longevity. Like all Noctua fans, the NF-A4x20 features an MTTF of more than 150.000 hours rating and comes with a full 6-year manufacturer’s warranty.


SpecificationsNF-A4x20 PWM 5V
Dimensions40 x 40 x 20 mm
Screw hole spacings32 mm
Connector4-Pin PWM
BearingSSO2
Blade GeometryA-Series with Flow Acceleration Channels
Frame TechnologyAAO (Advanced Acoustic Optimisation)
Rotational Speed (±10%)5000 RPM
Min. Rotational Speed (PWM, ±20%)1100 RPM
Airflow5.5 CFM
Acoustical Noise14.9 dB(A)
Static Pressure2.26 mm H2O
Max. Input Power0.5 W
Max. Input Current0.1 A
Voltage5 V
Voltage PWM signal 5 V
MTBF> 150,000 h
Accessories4-pin y-cable, 30cm extension cable, OmniJoin adaptor set, NA-AV3 anti-vibration mounts and Fan screws
Warranty72 months
EAN barcode9010018100136
SpecificationsNF-A4x20 PWM 5V
Dimensions40 x 40 x 20 mm
Screw hole spacings32 mm
Connector4-Pin PWM
BearingSSO2
Blade GeometryA-Series with Flow Acceleration Channels
Frame TechnologyAAO (Advanced Acoustic Optimisation)
Rotational Speed (±10%)5000 RPM
Min. Rotational Speed (PWM, ±20%)1100 RPM
Airflow5.5 CFM
Acoustical Noise14.9 dB(A)
Static Pressure2.26 mm H2O
Max. Input Power0.5 W
Max. Input Current0.1 A
Voltage5 V
Voltage PWM signal 5 V
MTBF> 150,000 h
Accessories4-pin y-cable, 30cm extension cable, OmniJoin adaptor set, NA-AV3 anti-vibration mounts and Fan screws
Warranty72 months
EAN barcode9010018100136

Customer Reviews

Used as a Jetson Nano heatsink fan

,

I planned on using a Noctua 40mm fan on the Jetson Nano before finding out that they are the recommended fan anyway. The NF-A4x20 Fan appears well built. After tapping the heatsink I used M3x8mm screws to attach the closest “ears” of the fan to the heatsink. I also tried the NF-A4x10 which is possibly a little quieter, but according to my basic “finger test”, the 10mm fan passes MORE air than the 20mm fan. I think this might be because the 10mm fan has more blade area and the Nano heatsink doesn’t have a lot of air resistance. I recommend the 10mm fan slightly over the 20mm but both work well.

Product Resources

FAQ

  • How do I measure fan size?

    The size of fan you need will generally be determined by the size of the fan fitting position in your PC case. The sizes of all the fans on our website are shown as measured along any one of the fan’s four sides, NOT the distance between the fan’s screw holes! Our most popular fan size is 120mm, followed by 80mm. This isn’t really dictated by customer preference, but more by recent designs of PC cases.

    As for the thickness (depth) of the fan, generally 25mm (1 inch) is by far the most common depth, although smaller fans can have shallower depths such as 15mm or even 10mm. All our fans are 25mm thick unless otherwise stated. If you have any questions about which fan you should order, please don’t hesitate to get in touch.

    If you know the distance between the fan mounting screw holes but don’t know what fan size to order, please see the following table. Note that the mounting hole measurements shown below are taken horizontally or vertically between the holes and not diagonally.

    Screw hole spacings and fan sizes

    32mm between screw holes:40mm fan size
    40mm between screw holes:50mm fan size
    50mm between screw holes:60mm fan size
    60mm between screw holes:70mm fan size
    72mm between screw holes:80mm fan size
    83mm between screw holes:92mm fan size
    105mm between screw holes:120mm fan size


  • I received a small cable (resistor) with my fan; what is it for?

    The resistor cable (also called Ultra Low Noise or ULN cable) is designed to allow the fan to run slightly slower for even quieter operation. The benefit in lower running noise is significant. Although the airflow will be reduced slightly, this usually has minimal effect on PC temperature. We would generally recommend using the ULN resistor cable for best results in almost all circumstances.

  • How can I tell which way the air blows through the fan?

    Hold the fan so that the round fan sticker is facing you. You are looking at the rear of the fan. When you plug the fan in, the air will be blowing towards you. If you want a fan to act as an air intake, then the fan sticker will be facing the inside of the case. Some fans also have two small arrows moulded into their plastic housing - one arrow shows the direction of airflow, and the other (at 90°) shows the direction of blade rotation.

  • Is it possible to use a 4-pin PWM fan or CPU cooler with a motherboard which has only 3-pin fan headers on it?

    Electrically, there is no problem doing this - the fourth pin on the fan cable is used purely for PWM control and is not needed in order for the fan to run. So you can plug the 4-pin fan connector onto the 3-pin motherboard fan header, leaving the fourth pin not connected to anything. The fan will potentially run at full speed, so if you would like to reduce the speed of the fan you will need to adjust the fan speed setting in your BIOS or use fan control software such as SpeedFan in Windows.

    The only other problem to consider is that occasionally, components immediately adjacent to the motherboard fan header can get in the way of the larger 4-pin fan connector, physically preventing connection. This problem also occurs if you try to use an in-line fan speed controller such as the one made by Gelid.

    Another avenue to explore is the possibility of using a bay-mounted fan controller. Several models are available now which provide 4-pin fan headers, so this is an easy way to use 4-pin PWM fans in a PC system which has only 3-pin fan headers on its motherboards. When using this method, you may find it necessary to disable any fan warning settings in your motherboard BIOS, since the motherboard may incorrectly believe that its CPU fan has failed when the fan is connected to a fan controller rather than directly to the motherboard itself.

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“Can’t recommend highly enough!”

“When I required a replacement for my PC, I stumbled across Quiet PC who were mentioned in an article in an online magazine. I found their website rather pleasant. It offers a good selection of components with obvious focus on low noise levels, but without sacrificing performance, and doesn’t overload the potential buyer with tons of options that are likely irrelevant. In other words, they focus on the components they know well. And that shows when you receive the PC (more in a moment).

For my build, I had a few customisation requests and questions: I needed extra cables prepared for disks and a graphics card I wanted to fit in, because I didn’t want to deal with cable management myself (If I had known how spacious the case is, I could have done it myself, though). Those requests were accommodated at no extra cost.

Any questions I had were answered within a few hours, and during follow-up email conversation it rarely took more than an hour to receive a helpful response. Absolutely no copy&paste style emails from Quiet PC! Service and communication has been excellent throughout the ordering process (and beyond).

When the PC arrived, I was positively suprised about the packaging as well as all the extra bits and pieces they ship with the computer: All manuals from individual components, all spare cables, lots and lots of screws for different purposes (put into nicely labelled bags), and even the remaining screws and brackets for the CPU cooler - including the CPU dust cover and extra thermal paste. In other words, you get all the original parts which weren’t needed in the build, and then some!

Before I first switched the PC on, I opened it to add all my disks and the graphics card. All the cables were prepared as I asked them to do. The cable management throughout was very neat and tidy. I have used other custom PC builders in the UK before, but none of them were even close to Quiet PC when it comes to cable management.

So, do Quiet PC build quiet PCs? Absolutely, yes, and without any sacrifice on performance or temperature levels. The case fans and Noctua CPU cooler keep the i7-6700K and the system temperature in the low 30C range during idle and normal office work.

I ended up replacing the case fans with Noctua fans, merely because I’m obsessed with noise levels and they are a bit quieter under load and can respond to raising temperature levels, but that doesn’t take anything away from Quiet PC’s choice -- The computer was already very quiet before, and the manual fan speed slider will be more than sufficient for the majority of users. (In fact you will hardly have to touch it; the idle airflow is good enough and you have to push the PC very hard to get temperatures beyond 55C for the CPU and low 40s for the system)

I apologise for getting carried away with this review! :-)

The bottom line is: brilliant service, including the option to have custom changes done; excellent build quality, packaging and spare parts; quick delivery (4 days in my case, instead of up to 7 as advertised). You can’t go wrong with these guys!”

(Review via Trustpilot)