Running 12 x 7970's which fluctuate around 8,000 kh/s in total.
I have 4 each in 3 rigs. I tried to get 6 onto a rig, but never got all 6 to run. I have a 1450W power supply which I thought would be sufficient, but maybe that is the limitation?
Yeah, 1450W is not enough for 6 7970's.
I have one machine running 2 7990's, 1 7970 and 1 6950, though it's requiring both 1000W & 750W power supply. This is basically 5 Tahiti's & 1 Cayman, which comes in close.
I'm using this 24-pin jumper to join the PSUs, and then powered risers for the 7990 to offload some of the current from the mobo. (
http://cablesaurus.com/Dual-PSU-24-Pin-Adapter-Cable)