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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:
- Standard Shipping : 3-10 business days
- If time is of the essence, please consider selecting expedited delivery for faster service.
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]
- Please click here for more details>>> Return & Exchange Policy
4.1 ★★★★★
Based on 2034 reviews
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Product Reviews
★★★★★ 4
Fun with a late blooming omega
Format: Kindle
I like this book. The story is fun, cute, and sexy. There's just a little drama, some excellent, steamy scenes, and a fairly good relationship building storyline. I especially like how all the main characters are a bit older than the usual 20 somethings I tend to see in this kind of book.
Having said that, I wish there were more descriptions of the places, as well as the food in the fancy restaurant. I enjoyed the cocktails at the club, so I missed that kind of detail when Gray took Madison on a dinner date. I also wish there had been more interaction between Lucas and Madison, and Lucas and Rian. It felt a bit lopsided, with a focus on Rian, Madison, and Gray.
I wish it had been proofread - there are a lot of typos, but nothing too distracting.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on September 12, 2022
★★★★★ 3
Madison Deserved Better
Format: Kindle
Madison was a beta...except she wasn't any longer. She was a late presenting Omega. And she was struggling. She was tall and thin, not tiny and curvy. She was opinionated. She was everything an Omega was not. After suffering through her first heat, her friends took her to Ardor, a club where Omegas came to safely find Alphas. She's not expecting much but then she connects with a sexy beta. And when she meets his Alphas, they set her body on fire. Maybe, she's found her no-strings-attached heat pack. Maybe, she's found something more.
I could not connect with the characters in this book, so their story never resonated with me. And there was no love story; there was sex. Grey made it clear from the beginning that he had a true love and it was his beta boy, Rian. He went so far as to reassure Rian “Say the word, I’ll never touch her again. Lucas can put the babies in her. I only need you, beta boy”. So, Madison was there for babies, no emotions needed. Nice. No, thank you. I want the Omega to be the center of their world, not an incubator. Lucas and Rian weren't any better. After her heat, they let her leave. Not one of them made her feel valued. No one gave her a reason to stay or even offered a cuddle. And the sex didn't even come across as mind-blowing. Madison deserved better.
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Reviewed in the United States on March 11, 2025
★★★★★ 5
No breakup, very sweet, instalove
Format: Kindle
Omegaverse and doesn't disappoint! Sweet guys, newly Omega FMC. The boyfriends are boyfriends. What's not to love? No angst, no breakup.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on February 23, 2025
★★★★★ 4
Pretty Darn Good
Format: Kindle
So I’ve been on a omega kick and this definitely hit the spot. Madison was frustrating at times with how she acted towards Lucas, Gray, and Rian. It was like she said towards the end, she didn’t believe she deserved nice things.
It would have been nice to hear from her best friends again. They kind of were there in the beginning and the gone except for mention of text messages received from them. I feel like her friends would have been great help in encouraging Madison to go with the pack and never give Brent another chance because he was toxic.
I loved Rian. His personality was awesome. His humor. His ability to make Madison comfortable whenever she was feeling overwhelmed. And the fact he fell for her and she fell for him first. They are cute together.
I do feel like Lucas was the odd man out though. Like Lucas didn’t develop as much of a relationship with Madison. I would have really liked to see more development in the relationship between them. It was also the same with him and Rian. There is really no relationship displayed. Most of the relationship being displayed is between Rian and Gray.
Nevertheless, I loved reading about the dynamic that came to fruition during the entirety of this story. Madison finally got her happiness. And Brent finally got punched in the face. Everyone got exactly what they deserve.
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Reviewed in the United States on September 6, 2022
★★★★★ 3
Pack's Promise was okay but not great
Format: Kindle
Pack's Promise was okay but not great. I won't recommend it to anyone that I know.
PRO:
* Very likable characters
* Lots of steamy scenes that are written very well
* The spelling and grammar are good
* The punctuation is good with the exception of using hyphens instead of commas. Lots of hyphens. Lots and lots of hyphens.
CON:
* Almost no interactions with any characters outside of Madison and the pack
* Nearly no plot. They meet, get together for a heat, agree to make it permanent, done
* Quite a few typos such as extraneous words, missing words and words out of order
THINGS TO KNOW:
* More steamy scenes than storytelling
* A lot of MM & MMM, some MFMM during heat
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on January 5, 2023
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