lol
and a complete toaster
I've yet to find a case that wouldn't basically torch everything inside it with four GPU's running full-out
heck i'm using HP Z800 cases and they can just barely handle running two R9 270x GPU's in them.  And all of the optional fans are in there.

for 4-GPU and up configurations, I've heard either milk crates or just custom cases are the way to go.