Yeah, I've thought of that too- the enclosure should dampen out any blade and electrical noise, but the air noise will be there. I hope to make the enclosure openings big enough that the turbulence will be minimal, and since the heat sink fins are running vertically, I plan to direct the air stream vertically also, so that there isn't the noise of the air blowing across the fins. How effective this is for cooling, I don't know. We'll have to see, I guess!
THanks for the interest.