Did some quick maths
ASSUMING that they use quad channel interface for each chip with the fastest ddr3 in existence and its 96GB not 72GB, that would make the total memory bandwidth of the rig 1TB/s which is 4 times faster than a RX580 or around 120MH/s. That would be the worst case scenario.
Thats incorrect, if they are using quad channel spread to 8 16bit 512MB DDR3 chips for each core thats ~14mh per core (assuming around a 1GHZ ram speed, some DDR3 can go up to 1600mhz. 14x 6 cores x 3 boards ~ 250 MH.