So I've been looking online, searching for a good deal on two 120mm case fans for an electronics enclosure I've got. I need a good bit of air flowing through there, so 120mm is a must. I see a lot of these fans that advertise themselves as quiet. But looking at the specs, their RPM and CFM is half that of the normal. That would make sense if you wanted to silence a fan a bit more. But, is that all there is too these "quiet fans"? It seems to me that they are charging more for a weaker motor. Am I missing anything?