In combination, the custom side panel and duct design provided a massive noise reduction compared to the stock configuration, particularly in lower fan speed ranges. We have measured around 7 dB(A) lower noise levels at around 50% fan speed, and up to 5 dB(A) lower at higher fan speeds, when compared at the same APU operating temperature.
While the custom side panel with our signature Noctua grill as well as the custom fan duct are not slated for mass production at this point, we are more than happy to share the 3D CAD files for everyone who is looking to make their Framework Desktop run even quieter.
Both the custom side panel and the customised fan ductare available to download at Printables.com for you to 3D-print at home
Yes, but the shape of the holes/grille also significantly affects acoustics, so it’s not simply a 1D scale for hole size scaling between “maximum airflow” and “maximum dust filtration”. I personally doubt the stock side panel is maximally efficient for the balance between airflow vs dust vs acoustics, and thus don’t think Noctua’s modded panel is purely “we made the holes bigger” improvement.
This article is very old but still gives an idea of things: https://www.pugetsystems.com/labs/articles/Effects-of-Grill-Patterns-on-Fan-Performance-Noise-107/