In my opinion, and soley based on my own personal research, that 400 watter would more than likely overheat the cab.
And something I'm pretty sure of based on experience, a computer fan that's capable of pushing 100 CFM is going to be just as loud as anything else that can push that many CFM. I have a 120mm fan that's capable of about 90 CFM, but if I crank it up that high she starts to make a real mean whine that can deffinetly be heard outside my own cab.
And it's not what the fan is mounted to that makes the noise, in case your thinking about isolating the fan, it's just the way those fans are designed. The motor makes the noise.
Sorry I can't help more.
Dizzy1 Reviewed by Dizzy1 on . Questions for a cabinet I've been planning a 3' x 2'-6" x 6' stealth grow cabinet for a long time now, but I have some questions before I get started. At first i was considering a 400w HPS light with batwing reflector. Seeing how my growspace is so small, I'm worried about heat. Assume temperatures around 75 degrees outside the cabinet. Is it possible to use the 400w HPS lamp with enough ventilation? If it is possible to use the HPS, what CFM fan will be adequate? Is a 125 CFM computer fan enough? Keep in Rating: 5