Noctua NA-IS1-12 Inlet Side Spacers Review
Introduction
Noctua is one of the industry leaders when it comes to PC cooling. They have been around for decades and their air coolers are both popular and proven reliable. Noctua is known for air-cooling products such as CPU cooler heatsinks and cooling fans. Today, we will be looking at the Noctua NA-IS1-12 inlet side spacers – a fan accessory that aims to further improve the performance of select Noctua fans.
The Noctua NA-IS1-12 is designed to complement Noctua fans installed on liquid cooling radiators – available in the standard Noctua color (NA-IS1-12) and black color (NA-IS1-12 chromax.black).
Noctua’s Take on the NA-IS1-12 Inlet Spacers
The Noctua NA-IS1-12 is a set of two 5mm thick intake side spacer frames for Noctua 120x25mm fans that can help to improve both acoustics and performance in suction or “pull” type applications where the fan draws air through obstacles such as grills, perforated plates, mesh panels, filters or radiators.
By offsetting the fan from the obstacle, the NA-IS1 inlet spacer reduces influx turbulences, which can, depending on the application and fan model, not only improve airflow but also significantly reduce overall noise levels and make the fan sound more pleasant to the ear.
Designed to replace the fan’s stock NA-AVP1 anti-vibration pads, the NA-IS1-12 is compatible with all current square-frame Noctua 120x25mm fans and extremely straightforward to install: For case fan applications, either the supplied self-tapping screws or the included NA-AV3 anti-vibration mounts can be used to sandwich the spacer between the fan and the case panel.
For radiator mounting, both M3 and UNC 6-32 screws are supplied. In sum, the NA-IS1-12 Sx2 set is a simple yet highly effective fine-tuning measure for suction type applications where a reduction of influx turbulence can lead to improved airflow and acoustics.
Closer Look
The Noctua NA-IS1-12 Sx2 has two inlet side spacers along with two sets of screws – M3 and UNC 6-32. It also comes with eight pieces of Noctua NA-SAV3 anti-vibration rubber fan mounts which are ideal for mounting Noctua fans on desktop cases. Lastly, eight pieces of long fan screws for case installation.
The Noctua NA-IS1-12 chromax.black comes with a similar set of accessories bundled with the two chromax.black inlet side spacers. The NA-SAV3 anti-vibration rubber fan mounts are also in chromax-black color.
The front side of the inlet side spacers has four rubber dampeners on each corner near the screw holes.
The back side of the inlet side spacers has two prongs on each corner, this secures the inlet side spacers in place on compatible Noctua fans. These prongs also make the inlet spaces incompatible with fans from other brands unless its frame has three holes in each corner like the Noctua fans.
Compatible Noctua Fans
The Noctua NA-IS1-12 inlet side spacers are compatible with mother 120mm Noctua coolers with the exception of a few models wherein the spacer’s prongs would make it incompatible. See the list of all 120mm Noctua fans below.
| Noctua 120mm Fan Model | Fan Dimensions | Max RPM | Compatibility with NA-IS1 Inlet Spacers |
|---|---|---|---|
| NF-A12x25 | 120x120x25 | 2000 | Yes |
| NF-A12x25 LS-PWM | 120x120x25 | 1200 | Yes |
| NF-A12x25r PWM | 120x120x25 | 2000 | No |
| NF-A12x25 FLX | 120x120x25 | 2000 | Yes |
| NF-A12x25 ULN | 120x120x25 | 1200 | Yes |
| NF-A12x25 5V PWM | 120x120x25 | 1900 | Yes |
| NF-A12x25 5V | 120x120x25 | 1900 | Yes |
| NF-A12x15 PWM | 120x120x15 | 1850 | No |
| NF-A12x15 FLX | 120x120x15 | 1850 | No |
| NF-F12 PWM | 120x120x25 | 1500 | Yes |
| NF-F12 5V PWM | 120x120x25 | 1500 | Yes |
| NF-F12 5V | 120x120x25 | 1500 | Yes |
| NF-S12A PWM | 120x120x25 | 1200 | Yes |
| NF-S12A FLX | 120x120x25 | 1200 | Yes |
| NF-S12A ULN | 120x120x25 | 800 | Yes |
| NF-F12 industrialPPC-2000 | 120x120x25 | 2000 | Yes |
| NF-F12 industrialPPC-2000 PWM | 120x120x25 | 2000 | Yes |
| NF-F12 industrialPPC-2000 IP67 PWM | 120x120x25 | 2000 | Yes |
| NF-F12 industrialPPC-3000 PWM | 120x120x25 | 3000 | Yes |
| NF-F12 industrialPPC-24V-2000 SP IP67 PWM | 120x120x25 | 2000 | Yes |
| NF-F12 industrialPPC-24V-3000 SP IP67 PWM | 120x120x25 | 3000 | Yes |
| NF-P12 redux-1700 PWM | 120x120x25 | 1700 | Yes |
| NF-P12 redux-1300 PWM | 120x120x25 | 1300 | Yes |
| NF-P12 redux-1300 | 120x120x25 | 1300 | Yes |
| NF-P12 redux-900 | 120x120x25 | 900 | Yes |
| NF-S12B redux-1200 PWM | 120x120x25 | 1200 | Yes |
| NF-S12B redux-1200 | 120x120x25 | 1200 | Yes |
| NF-S12B redux-700 | 120x120x25 | 700 | Yes |
| NF-S12A PWM chromax.black.swap | 120x120x25 | 1200 | Yes |
| NF-F12 PWM chromax.black.swap | 120x120x25 | 1500 | Yes |
| NF-A12x15 PWM chromax.black.swap | 120x120x15 | 1850 | No |
| NF-A12x25 PWM chromax.black.swap | 120x120x25 | 2000 | Yes |
To learn more about Noctua’s 120mm fans, please visit the Noctua website.
Installation
The majority of the 120mm Noctua fans that are compatible with the NA-IS1 inlet side spacers have anti-vibration rubber pre-installed on each corner of the fan’s frame.
To prepare the fan for the inlet side spacers, simply remove the anti-vibration rubber on all four corners of the fan’s frame. Whether you plan to use the fan for pushing air or pulling air, remove the anti-vibration rubber on the side of the fan wherein the inlet side spacer goes in between.
anti-vibration rubber removed 
inlet side spacer installed
anti-vibration rubber removed 
inlet side spacer installed
The Noctua Redux Series fans do not have anti-vibration rubber on their fan frame. Thus, users can install the inlet side spacers immediately.
Below is a comparison between the Noctua NA-IS1-12 inlet side spacers and fan installed and the fan alone. Notice the small gap between the inlet side spacer and radiator, there’s a small opening for air to leak. Let us discuss this later in our testing.
[Important!] The included M3 and UNC 6-32 screws must not be used for mounting fans into radiators without the NA IS1-12 inlet side spacers. These screws are longer and designed to cover the added height. Using these screws to mount fans without the inlet side spacers poses a risk of puncturing the radiator.
Performance: Noise Reduction
The Noctua NA-IS1-12 inlet side spacers offer two things – improved performance and reduced operating noise. Let us first take a look at noise reduction. There is a slight noise reduction when you use the NA IS1-12 inlet side spacers on Noctua fans. I tried the inlet side spacers on three 120mm Noctua fans in both pushing air and pulling air configurations. Check out the results below.
Noise Test 1: Noctua NF-12 industrialPPC 3000RPM 24V Pushing Air Through Radiator (Back End Test)
without inlet side spacer 
with inlet side spacer
For test 1, I used a Noctua NF-12 industrialPPC 3000RPM 24V fan running at 12V 1980 RPM, pushing air through a radiator. The inlet side spacer appears to slightly reduce noise when you check the noise levels at the radiator’s end.
Noise Test 2: Noctua NF-A12x25 PWM Pushing Air Through Radiator (Front End Test)
without inlet spacer 
with inlet spacer
For test 2, I’m using a different fan configured to push air through the radiator but the fan is still running at maximum RPM at 12V. Noise is tested on the front end of the fan unlike in test 1 that’s measuring the noise on the back end. The inlet side spacer doesn’t seem to have any impact on the noise level on the front end wherein the fan sucks air – the difference in noise level is too small to be significant.
Test 3: Noctua NF-A12x25 PWM Pulling Air Through Radiator (Back End Test)
without inlet spacer 
with inlet spacer
For test 3, the fan is pulling air through the radiator at 12V max RPM – the configuration users would commonly use with the radiator installed behind the front panel of the case. Noise reduction is much more obvious when noise is measured where the airflow exists.
Test 4: Two Noctua NF-A12x25 PWM Fans Pulling Air Through Radiator (Back End Test)
For test 4, I will be testing three different configurations with the NF-A12X25 PWM fans specifically with the third configuration using the anti-vibration gasket for radiators – an accessory included with the NF-A12X25 PWM. Noctua released 140mm versions of the anti-vibration gasket which I will review later.
In all three configurations, the fans are running at 12V at maximum RPM. Noise reduction is a different story when you have more fans making noise. Still, the Noctua NA-IS1-12 appears to reduce noise even just a little. However, the anti-vibration gasket offers superior noise reduction. The anti-vibration gasket totally seals the side of the fan’s frame to the radiator leaving no opening for airflow to leak. The anti-vibration gasket cannot be added to the spacer inlet and thus cannot be tested unless the gasket is permanently modified.
In all the configurations I’ve tested, the noticeable change in the noise the fans produced is how it went from a high-pitch sound to a lower-pitch sound when the spacer inlets are used. Personally, a low-pitch sound is desirable compared to a high-pitch sound. Now let’s move on to testing the airflow improvement the NA-IS1-12 inlet side spacers also offer.
Performance: Airflow
For testing airflow, I’m simply measuring the volume of air the fans are pushing with and without the inlet side spacers using an anemometer. I do not have fancy airflow testing equipment and setup but this test should give a good picture of how the fans work with the spacer inlet.
In this test, the Noctua NF-A12X25 PWM fan is running at 12V at maximum RPM, pulling air through the radiator just like in test 4 above. Air is blown by the fan at a rate of 2.7 meters per second.
With the NA-IS1-12 inlet side spacers installed, the NF-A12X25 PWM fan is pulling air through the radiator and blowing it at a rate of 3.1 meters per second. The increased airflow would mean better heat dissipation for liquid cooling systems – pulling air through the radiator faster.
Conclusion and Final Thoughts
In my tests, the Noctua NA-IS1-12 inlet side spacers improved acoustics and airflow with fans used in radiators. The differences are barely noticeable when you are relying on your senses alone. The difference in performance and acoustics are more pronounced when you use a proper measuring device like a sound meter and anemometer for this review’s instance. The improvements are not drastic which would make these game-changing accessories. Nevertheless, an improvement is an improvement.
If you are already using Noctua fans for cooling your radiator or chassis, the Noctua NA-IS1-12 inlet side spacers offer a bit of an upgrade. Its value would differ per builder as a pair of these sells for $14.90 – quite an investment considering that the 120mm Noctua Redux fans are around the same price. Nevertheless, the inlet side spacers do complement all compatible Noctua fans.
Now the real question to ask here is this – do you really need the Noctua NA-IS1-12 inlet side spacers? Perhaps not necessary particularly if you are already using the premium Noctua NF-A12X25 PWM fan which is already incredibly silent for its class. The Noctua inlet side spacers appeal to the purists and enthusiasts that simply want more out of their Noctua fans. The inlet spacers are also ideal for Noctua fans installed on cases.
In conclusion, I would recommend the Noctua NA-IS1-12 inlet side spacers for purists that have the money to shell out for better acoustics and performance. These spacers available in Noctua’s standard color and chromax.black to color-match with the compatible Noctua fans.
Pros
- Improves acoustics
- Improves airflow
- Aesthetically complements compatible Noctua fans (in color)
- Complete assortment of accessories for radiator and chassis use
Cons
- Only compatible with Noctua fans
Buy the Noctua NA-IS1-12 Sx2 for 120mm Fans on Amazon
Buy the Noctua NA-IS1-12 chromax.Black Sx2 for 120mm Fans on Amazon
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