Currently, there are 30 GPU's in my farm total. 5 rigs of 6 cards each. 4 of the rigs are running Gigabyte R9-380's, 6 cards each for 120 MH/s per rig. I built one rig, using 6 of the R9-290/390 family that hashes at 180 Mh/s.

PSU's on the 380 rigs are EVGA 1300 watt Gold rated. PSU on the 290/390 rig is EVGA 1600 watt Gold rated.

All Asrock BTC H81 Motherboards, Celeron Dual cores, Powered USB 3.0 1x to 16x risers.

5 Dedicated outlets in my garage off the electrical panel. $0.10 KWh costs.