my guess...
...is that its a passive backplane with a couple of specialized (ha ha) boards linking them together.
Some of the feeds and speeds of the Chinese government's Tianhe-2 massively parallel ceepie-phibie supercomputer leaked out in May and then even more came out a week later ahead of the planned big splash at the International Super Computing shindig in Leipzig, Germany. But El Reg has some juicy pics of some of the key components …
What's even more amazing, is that our grandchildren will one day see such components preserved in a museum, and will look upon them as wonderful achievements of an age of unbelievably primitive technology aeons away from what they will be using and dealing with, in a very different world.