Cooling using Computer Case Fans

[flurin]

I agree, a duct needs high pressure fans or air pumps.
I used the NMB 3612KL-04W-B66, 3'800 RPM, 70 CFM. It isn't so high as you proposed but not so bad too.
One problem with ducts is that the fan intake side is open and this leads to back-flow, especially if the fan runs at full speed.