I wanted to upgrade my stock part cooling fan to a pair of noctua 40mm fans and when I did a test run they barely push any air through the ducts compared
Platine CM Noctua - 40x40x20 by Kyrian | Download free STL model | Printables.com
Noctua NF-A Series Review (Page 1 of 4) | APH Networks
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$14.99 - Fan 40x40x20 5V 4 Pin PWM Noctua Nf-a4x20 5000 RPM Chipset Fan - Tinkersphere