I've read in reviews that at its lowest setting its silent but at high it is audible, but if you already have two 120mm fans goin, you're probably not goin to hear it. The cross-flow fan in concept is a very good idea I just wish they wouldn't gouge you for it(thirty bucks for a fan? I mean, come on)when in concept its really supposed to come with the case since it only works with the Stacker case. I think the way they market the case even on the box itself is somewhat deceptive(not like Asus)even tho they do state the crossflow fan is optional. To a passerby however it would seem like the fan comes with but meh, oh well. Just another manufacturer trying to make an easy extra buck I guess.
