The fans are noisy? You could only have one fan and it could still be noisy. It all depends on the age and condition of your fans. You could have the bearings going out of one or something. Some fans are just noisy too.
Would a case cause the fans to make a lot of noise? The case I'm using is extremely light, and it seems the fans make a LOT more noise when they're attached to the case than when I hold them in my hand.