Is it turbulence? It's a common issue with the Fractal Terra case if the fan is too close. Obviously, you can move the spine back a bit to fix it. Not sure about how you would fix it on the ridge though.
"I regret buying the Fractal Ridge case instead, it is a nice compact case but somehow the shape of the ventilations holes make my case so noisy, if I just remove the side panel the noise levels go down significatively."
@sarkwalvein
"You can buy it again and ship it to me. I would put it to good use"
What's your address? :creep:
"Actually, is your PC in this case silent or loud? I wonder if it is quieter than the Ridge."
I'll make an update after Christmas :)