You can go with a good case which is sure to have minimal noise. Corsair is one of the best brands but that case is a mid tower.If you truly want a super silent performance with up to 4 graphic cards inside I recommend you the Enermax Thormax Full Tower case.
Just google it as I am at work and I am using the phone because spies are all over me as in any other company I think.
well I was thinking about something more lowprofile, of course I don't want people to know I'm mining there, so I need a good case that looks more like an office case. THis Carbide silent series has a full tower too
https://www.amazon.com/Corsair-Carbide-Quiet-Inverse-Tower/dp/B016IAM7AQBut wouldn't putting more than 2 cards be exponentially louder and hotter for a closed case? I said only two simply because of that, but I don't really know it to be honest, can't find any tests about this,