First post here, so please feel free to redirect if required
I've just received my CRS328-24P-4S+RM which looks excellent; however, as others have noted here the "typical" fan noise is not "house" friendly. I'm therefore planning to replace the existing two fans with Noctua NF-A4x20 PWMs.
The installed fans are Sunford AD4028V12BLBGF's. I've not been able to find the exact specs for this fan, but from what I can deduce from the Sunford AD4028GF series specs the closest match is the AD4028V12_LWGF with 11.61 CFM airflow and 12.15 mmH2O static pressure. By comparison, the Noctua NF-A4x20 PWMs have 5.5 CFM airflow and (only) 2.26 mmH2O static pressure.
The static pressure is my main concern here, as my PoE usage will be limited and with low wattage requirements. Accordingly, I'm planning to replace the existing Sunfords and install two further fans (4 in total) in the fan3 and fan4 slot.
My question regards the direction (push or pull) that I should install fan3 and fan4. fan1 and fan2 as currently configured are operated in pull mode (air pulled from inside the case to outside). My inclination is therefore to install fan3 and fan4 in push mode, so that they draw cool air into the case, and in general the airflow is maintained right to left across the unit.
Does anybody know in which direction fan3 and fan4 are intended to operate?