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Description
Noctua NF-A4X20 5V PWM 40x20mm Premium Cooling FanFeaturing 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 Noctuas highly optimised, premium quality quiet 40x20mm fan. The custom designed NE FD3 PWM IC that integrates Smooth Commutation Drive technology and Noctuas reference class SSO2 bearings guarantee superb running smoothness and excellent long term stability. Topped off with modular cabling, the
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.
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.
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.
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.
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.
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.
Technical Specifications
Size: 40x40x20 mm
Mounting hole spacing: 32x32 mm
Connector & pin-configuration: 4-pin PWM
Cable length: 20cm + 30cm NA-EC1 extension cable
Bearing: SSO2
Blade geometry: A-Series with Flow Acceleration Channels
Frame technology: AAO (Advanced Acoustic Optimisation)
Rotational speed (+/- 10%): 5000 RPM
Min. rotational speed (PWM, +/-20%): 1100 RPM
Airflow: 9,4 m³/h
Acoustical noise: 14,9 dB(A)
Static pressure: 2,26 mm H₂O
Max. input power: 0,5 W
Max. input current: 0,1 A
Operating voltage: 5 V
Voltage: PWM signal 5 V
MTTF: > 150.000 h
Warranty: 6 years
Package includes:
- Noctua NF-A4X20 5V PWM Cooling Fan
- 4-pin y-cable
- 30cm extension cable
- OmniJoin™ adaptor set
- NA-AV3 anti-vibration mounts
- Fan screws
Shipping Notes
- Free Standard Shipping on $100+ Orders to the USA.
- Except Preorder products are shipped in 48 hours.
- Delivery to the USA:
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Exchange/Return Notes
- We offer a 30-day return/exchange service after receiving.
- Final sale items are not eligible for returns or exchanges.
- To process your return/exchange, please contact us at [email protected]
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4.3 ★★★★★
Based on 2355 reviews
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Product Reviews
★★★★★ 4
Four Stars
Format: Hardcover
great for the 80/20 library
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Reviewed in the United States on April 26, 2016
★★★★★ 5
Book Review of The Alchemist
Format: Paperback
In The Alchemist, Paulo Coelho uses diction, syntax, and the hero cycle to keep the pace of the book constant, and keep the reader intrigued. But, he does have a few flaws present in the book.
The Alchemist is a book about a boy named Santiago, who goes on an adventure to find his “Personal Legend” or treasure. Coelho uses the hero cycle to add more emphasis on the plot, which overall makes the story more entertaining. In the story, the Old King tells Santiago that “when someone wants to realize his or her Personal Legend,” he will “always [be] nearby.” (67) This is an example of atonement with the father, because the Old King’s closeness creates a father like figure in him, who is there to support Santiago. The hero cycle for me made the story more enjoyable and kept me reading. Also most of the book is him trying to obtain his Personal Legend, which is “what you have always wanted to accomplish.” (23)
Compared to other books I have read this year in my English class, this one was easier to follow in terms of diction. The language that Paulo Coelho uses in the novel overall is not too difficult to understand. Word choice is done very well, and lets the reader flow through the book at a constant pace. The diction also makes the book a novel for a wide range of readers. The hero cycle with the clean diction made the story very enjoyable.
While reading this book, I found that it was fairly easy to understand the passage, and that it was very inviting. Paulo Coelho structures the syntax of the book in an easy-to-understand format. Throughout the book, the syntax helps the reader understand where they are on the page, and it also positively affects the pace set by the diction in the book. Towards the middle of the novel, the boy says that “An army is coming,” and he knows because he “had a vision.” This dialogue is quickly followed up by a response from a camel driver, saying that “the desert fills men’s hearts with visions.” (104) The quick pace of dialogue keeps the book driving keeps the pace constantly in motion. The syntax made it easier for me to follow the story and follow which character was speaking and what they where feeling or doing.
Even though I enjoyed a great bit of the book, there was still another bit that I didn’t fully enjoy. At the beginning of the Alchemist, the book seems to go a slower speed then the rest of it. The first portion of the book has a lot to do with introducing Santiago, the plot, the setting, and more. There is a part in the story where it goes from page 35 to page 38 with very little dialogue, which I felt stopped progress of the story. The first part also has to do a lot with how he discovers his Personal Legend. It took me a little while longer to read the first part of the book then the rest because I was mostly bored while reading it. I also felt that there was more descriptive text than the rest of the book, which really dragged out the first part.
In conclusion, the book has lots of great traits and only a few bad ones. I would definitely recommend this book to a friend or anyone who enjoys reading about adventure.
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Reviewed in the United States on January 12, 2016
★★★★★ 5
such an adventure
Format: Kindle
Loved this!! Lots of questions to ponder and the simplicity of it all 🫶🏻. A short read but so very profound
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Reviewed in the United States on May 22, 2026
★★★★★ 4
Interesting story
Format: Paperback
The Alchemist is an engaging modern fable centered on self-discovery, personal destiny, and following your dreams. It offers interesting life lessons and an easy-to-read story. While its themes draw on various spiritual ideas and may feel unconventional, it still delivers meaningful reflections on purpose and perseverance. Overall, a thought-provoking and enjoyable read.
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Reviewed in the United States on April 26, 2026
★★★★★ 5
One Of The Most Important Books Ever Written
Format: Paperback
The Alchemist by Paulo Coelho is in my opinion, one of the most important books ever written. It's no wonder that it's one of the best-selling books of all time with more than 150 million copies sold. Those numbers are in spite of and defiance to the author's encouragement to file share his now legendary novel.
But sales statistics are not the criterion on which I stake this claim. It is the impact on the lives of those that have read it, and the impact on the lives that have not yet been born, that I boldly state the above.
The simplicity of its unfoldment may at first belie the depth of its wisdom. But the simplicity is part of the profundity that allows the reader to assimilate the messages without resistance.
The first time I read The Alchemist;, I read it cover to cover in one sitting. No bathroom break, no cup of water pause, no telephone distractions. I read it from the first word to the last in what seemed like a single breath.
I simply couldn't put it down.
I was swept, swung, and swallowed up by this extraordinary narrative. The result was transformation. I was not the same man that began reading the novel by the time I finished it.
I would thereafter read it again and again. The messages are so layered that with every new pass comes new understanding and enlightenment.
At the core of the novel is the fulfillment of one’s destiny. There is a force in the Soul of the World that wants us all to live out our personal legend. When we truly desire something, the entire Universe conspires to help us achieve it. With love, all things are possible. With love, we can perform miracles.
These themes are artfully integrated and clothed within a modern day fable. They come in varying iterations from a string of colorful characters that propel the protagonist towards a profound and satisfying ending.
The Alchemist is the story of Santiago, a shepherd boy from Spain that crosses the desert of Africa in search of a hidden treasure. It was revealed to him in a reoccurring dream that the treasure is buried by the Ancient Pyramids in Egypt.
What he naively believes will take three weeks to complete becomes a journey that expands nearly three years. After miles of traveling through the desert, the boy arrives at an oasis where he falls in love with a beautiful desert woman named Fatima. The boy is willing to abandon his dream of finding his treasure for the procurement of her love.
But one night, beneath the light of a full moon, he meets a man straddled upon a mighty horse. This elusive man is known in legend and folklore as The Alchemist.
The Alchemist is a man imbued with profound wisdom and mystical powers. He is reportedly over 300-years-old and can turn lead into gold.
He reminds the boy that his destiny is to find the treasure. That he must continue. If it is true love, Fatima will be waiting for him after his destiny is fulfilled.
Reluctantly, the boy continues his journey deeper into the desert accompanied by The Alchemist. But the desert is at war, and they are soon captured by Bedouin sentinels and accused of spying for the enemy.
For this crime, they are sentenced to death.
The Alchemist saves them temporarily by proclaiming that the boy is an Alchemist. He tells the general that if he wanted to, the boy could turn himself into the wind and destroy their entire camp. The general is intrigued! He wants to see this happen. He promises to spare their lives if it is done. He grants them three days.
But how does a shepherd boy from Spain turn himself into the wind?
Paulo Coelho says that he wrote “The Alchemist” in two weeks. It is almost hard to imagine that something so far-reaching could have been conjured up in two weeks time. He said it was his own journey that he was writing down, parabolically speaking.
The impact of “The Alchemist” comes from the realization that Santiago’s journey is Everyman’s journey. His story is our story. If we tap into the Soul of the World and dare to live out our destiny, we will discover that within us all is The Alchemist.
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Reviewed in the United States on April 21, 2017