Multi-gpu new build parts advice needed

I'm working on a project build starting from an odd point... I have the following parts:
Super micro motherboard (h8dgi-f, EATX form)
Two amd opteron CPUs (6344)

I'd like to turn this into a mini supercomputer, using multiple GPU boards. I really could use advice on chassis, cooling, gpu boards, power supply (basically everything but the three parts I currently have).

Thanks!