Caulk. Silicone caulk can be used to create custom vibration absorbing gaskets where metal meets metal. I used it in a custom case that I made to great effect.
If the offending joint is permanent, just squeeze some caulk into the gap and push it in with a toothpick if you have difficulty getting it to flow into the gap.
If the offending joint is meant to separate, put vaseline on one side of the joint, apply a bead of caulk to the other side and mate the two surfaces. The vaseline helped the caulk not stick to one of the two sides in my case. When the caulk is cured, take the joint apart and remove the vaseline.
First time post, I'm building my first silent PC (update)
Moderators: NeilBlanchard, Ralf Hutter, sthayashi, Lawrence Lee