To my surprise, my brand new X-Controller was too noisy out of the box as shown at the 1:18 mark of the video below:
I tracked down the problem to vibration from the cooling fan being transferred through its M3 screws to the Controller Board and then to the chassis. Once the contact points were eliminated, the excessive noise went away.
Did your X-Controller have this noise issue?
Note: this X-Controller was purchased at the end of 2016 but finally got around to building it recently. I would imagine Inventables fixed this issue long ago.