The noise level of mechanical keyboards is a function of the keyswitches being used. From your comment I'm assuming you got the black or brown switches?
I have a Corsair K90 with cherry red switches, which are still quite noisy - the noise comes from the keys bottoming out, rather than the switch itself.
You can get little rubber rings to dampen them though.
I really like how the Leopold types and it's not frustratingly loud like many mechanical keyboards.