If you have the space, the upgraded fans look like a very good idea - though a 6 watt fan isn't super heavy duty, it's probably a good bit more than the average factory fan and probably flows a lot more air.
Happy to report that gpuShack will now be using 15W fans instead of 6W fans for all mining GPUs (link in sig).
If I have 6 graphics card in the rig, the power consumption of the fans will be 90W if you use one each graphics cards. That is quite a lot.