This is an adaptor for a 40mm fan to replace the super loud stock one with an equivalent but super silent Noctua fan. As you can see below I choose a fan that has a slightly higher airflow than the stock one to ensure proper cooling when using the adaptor. Also, I designed the adapter such that the fan now sits right behind the rear air intakes and can suck in fresh cool air from the outside. The Noctua model I choose even comes with an adaptor that lets you connect 12V directly to the fan so no soldering or cutting off plugs required. The adaptor mounts in the same position as the original fan using the stock screws. All you need is 4x 3mmx25mm socket head screws or similar to mount the new fan. This Upgrade is completely reversible in case you don't like it. Any feedback you have is very welcome. If anybody has a Mars 2 pro and can test if this upgrade is compatible with it I would be grateful.

stock fan: Coolcox BF4020H12S 12V 0.15A 4.9CFM / 8.3m^3/h measured at about 40-45dB with my phone at 15cm

replacement: Noctua NF-A4x20 FLX 40x20mm 12V 0.05A 5.5CFM / 9.4m^3/h 14.9dB according to Noctua