A large, solid case with big, solid fans running at slower RPMs is a recipe for a quiet case. You've chosen the word "silent", which is a strong word to use in this case. A "silent" case has no noise. That means no fans, which means you need a different way to get rid of the heat. This kind of case is likely to be closed in with a fluid piping out from the case to a heat reservoir. I imagine you weren't looking for this solution though.