Wrt. noise: decibels (dB, "perceived loudness") are logarithmic in sound energy, so going from e.g. a single GTX 1080 at 47 dB to 8x GTX 1080 only increases the noise to 56 dB, which is noticeable but not really annoying, and very far from requiring ear protection. Recommendations for office spaces is that noise be kept < 60 dB IIRC.
Wrt. cases: I think a regular E-ATX compatible case should be enough, but it all depends on the motherboard, and those don't exist yet. Existing 8x GPU servers have been 4U rack mount dual socket affairs; you can also already get 7x GPU dual socket "EEB" motherboards and workstation style cases, but none that will do full 16x for all the GPUs.
