I would suggest that the first thing to do is by hearing protectors.

Haha, well we have the replacement fans ready to install. And these will be in a server room kept nice and chilly.
We will be selling off some of our B7 / B8 S3+ units to free up some PSUs. Perfect condition, housed in Server Room at 64 F (approx) Hepa Air Handler. Clean and Like New.
I apologize if this is off topic but if there is any interest just shoot me a PM.
Strato
I am curious though. If these are in a server room, why tinker with the fans at all? Is there a noise concern in the room? I thought the issue with the S5 fan was strictly noise related.