My friend and I have started building our 12.6gh/s mining farm. Right now we have 8 rigs with 6 GPU's each.
Current 8 test rig setup (6x Sapphire Nitro+ RX 580's (8gb) per rig)
Each rig is doing 180mhs to 188mhs. We have already bought all the parts for the next 62 rigs. I will update with a detailed walk through of our setup as we build it out.