I saw somewhere that they were using custom built hardware modules to break AES keys, some kind of FPGA thing. It was cheap to build and extremely fast since it was specialized in doing just that.
Intel 3930k = 66.6 Mhash/s AntMiner S9 ASIC = 14,000,000 Mhash/s
So that's only 74074 Mh/s per ASIC.
Granted, that's still wiping the floor...