hmmm... hmmm if that is how you get your bj's so be it.... lol, j/k
would it not make more sense to find a more efficent method of cooling your case. Or better yet design you air movement system so as to allow you to cut down on the number of fans and the noise.
Tell me this. Those HD fans, they are 40's right. Does not the high pitch whine they make not get on your nerves? (Assuming that they are running at a very high rpm like 60's do...)