Re: Against noise: does it exist some computer cases / tower completely silent?
Just use Noctua fans for your chassis fan and your CPU cooler fan, and a passive-cooled video card. That'll be as close to silent as you want.
Don't worry about what the other poster said about Noctua fans - they are so quiet that you don't need to run them slower. And they come with two special adapters that run them slower, anyway.
I try to treat the cause, not the symptom. I avoid the terminal in instructions, unless it's easier or necessary. My instructions will work within the Ubuntu system, instead of breaking or subverting it. Those are the three guarantees to the helpee.