Like all of the gear we see from Noctua, nothing is ever simple – the designers have jammed the S12A full of technology to make them more efficient in terms of airflow to noise ratio. Much of the technology has been implemented in their recently released products and it is good to see a company consistently improving its range of products this way. The main thing we noticed on the S12A that we didn’t see in the A14/15 products was the implementation of Anti Stall knobs on the blades.
Anti Stall Knobs are found on each impeller blade and look like little ‘bumps’. The angle of the impeller blades on the S12A and the older S12B is higher than many other fans in order to improve airflow. The downside of this design is that the airflow efficiency is impacted more so by an exhaust obstruction and it has a higher tendency to stall. This means that the new S12A fans are more suitable for heat sinks and radiators than the previous S12B model but still not as effective as the NF-F12. We think that the anti stall knobs are more likely to be of benefit in situations where you are trying to push air through a case grill and don’t really want to mod your case with a Dremel to improve the airflow.
The Advanced Accoustic Optimisation (AAO) Frame has the anti vibration pads, stepped inlet design and inner surface microstructures. We saw this same design on the NF-F12 and NF-A14/15 reviews.
The stepped inlet adds turbulence to the intake in order to reduce tonal intake noise, improve flow attachment to the frame and increase suction.
This all translates to less vibration being transferred through the chassis and higher airflow through the inlet because the air hugs the frame. The creation of a boundary layer of air via little dimple microstructures also improves efficiency. These technologies all combine to reduce the ‘wind’ noise and at the same time, increase the airflow. Noctua have changed the majority of their products to use the AAO frame now so we can’t question their commitment to the design or the science.
Here are the Noctua diagrams that illustrate the engineering specifics of the frame a little better:
We see the implementation of the SSO2 bearing (also seen in the NF-F12) where the rear magnet is located closer to the axis in order to be more stable and precise than the previous SSO. This also increases durability and Noctua back the product with a 6 year warranty which is pretty good for something that spins at 300-1200 rpm. The Mean Time Between Failures is rated at 150,000 hours (6,250 days / ~17 years).
There is other technology implemented here that we saw previously in the NF-F12 such as a brass bearing shell and Smooth Commutation Drive 2.