A totally different type of fan than the ones we normally deal with. The Arctic S12038-4K is designed for high-performance servers, which is also reflected in its features. Very high airflow is provided by as much as 4000 rpm. And in order to ensure that the cooling performance does not drop significantly even through obstacles, the “extreme” Arctic fan has a profile that is as thick as 38 mm.
The impeller of the fan has a rather unconventional shape. Arctic built it on five blades, as they do with the most popular P fans. However, unlike them, the S12038-4K’s blades stretch more in width than in length. They are thus relatively short, which is important considering that the maximum specified speed is up to 4000 rpm. This design (shorter and wider blades) should be less subject to unwanted flight deformations that would also translate into high vibration. Arctic also wanted to avoid these, or keep them to a minimum.
The wide blades are also important for achieving high static pressure, which is a major focus of the S12038-4K. Although the outer cross-section of the impeller consists of only five blades, the gaps between them are very small from a frontal view. This design contributes to keeping the negative effect of back pressure to a minimum. In other words, the drop in airflow through an obstacle should be as low as possible.
For extra high static pressure, the fan profile thickness is up to 38 mm (instead of the usual 25 mm). The specifications state up to 11.45 mm H2O and our tests confirm this value. While maintaining the same speed, this fan’s drop in airflow through an obstacle is relatively small.
Also noteworthy is the design of the impeller hub with a tiny built-in fan with a diameter of approximately 34 mm. Its main role is to cool the motor, resulting in lower temperatures and a longer overall service life. This is particularly useful in environments with excessive ambient air temperature. However, if the fan operates in dusty environments, it is advisable to cover these small blades. For this, there is actually a self-adhesive cover that is included in the accessories. The Arctic S12038-4K has no protection rating (IP) and so excessively dusty environments will never be an optimal destination.
And how is the noise level with and without the cover? Very similar. Anyone who would have assumed higher noise levels without the cover (because of more edges cutting the air) at higher frequencies would be wrong. It’s like a carbon copy, and in this respect it makes virtually no difference whether you use it or don’t (and leave the hub “exposed”). This is evidenced by the spectrograms at maximum speed. Even around 3629 rpm (at 100% PWM duty cycle with 12.00 V pulses) is too low a speed for the activity of the small impeller to cause an audibly different acoustic profile. In any case, the overall noise level of the S12038-4K fan is very high at maximum speed. However, a significant speed reduction is also possible. Arctic lists 600 rpm as the lower limit, we measured 455 rpm. You can’t force the fan to run passively with PWM control, the motor doesn’t stop even at very low (PWM) duty cycle.
The cable is simple – flat, 33 cm long, terminated with a 4-pin connector.
The weight of the fan is also worth mentioning. It is up to 324 grams, with which the Arctic S12038-4K is sovereignly the heaviest 120 mm fan in our tests. If you’re interested in technical details on the MTBF value, Arctic has detailed documentation with the dependence of this value on the nature of the usage environment. The bearings used are ball bearings, double row with a brass sleeve. A summary of the basic parameters is included in the next chapter of the article. By the way, in addition to the tested variant, there is also the even faster S12038-8K model with speeds up to 8000 rpm.
you should test the 8000rpm version. that is the holy grail – 3+3 push/pull on the AIO, 3 on the GPU, 2-3 case front, 1 case exhaust, 2-3 case base
And when the PWM fails, the pc just slams the door 😹