I could not find any fans for sale that moved air well that were made to be silent like the S&P Mixvent. I have the smaller version and it is the stealthiest I have achieved after trying two other fans. I think it is impossible to move the amount of air you need and be silent. If you got 5 computer fans going it would maybe keep up with the heat, but it would probably be just as loud. The air movement creates most of the sound. So if you are looking for ultra stealth you may need to scale back the grow and use CFL only and go back to the computer fans. Problem with that is that when it comes time to control the smell, you are going to have a hard time getting those fans to blow through a carbon filter.