To get the most I could (power out of 15A home circuits that is...), I used two circuits (15A each) to split 3 rigs onto.....that looks like this:
(1 full machine & 'in-window' twin cooling fan per circuit, 3rd rig split over 2 circuits to keep from blowing breaker)
Circuit A also has a Dell 24port 10/100 switch (almost forgot about that...lol
All cards running @ 950Mhz GPU / 900Mhz Mem @ 1.02V, 565MH/s per card....(using CGMiner 2.4.1 defaults, Win7 x64)
Both of the remaining 4-card rigs will also get their 5th 7970's installed as soon as the cards arrive.
Hope this helps some people, or gives a few ideas for those wondering....
For those wondering about specific setup...(not including the obvious single power supply 5-card/1200W PSU Rig)...
On the 2x PSU rigs, I use the 850's to power the Motherboard/CPU/HDD + 2 Video Card's External 8pin/6pin connectors (and of course all PCIe Slot Power by association).
The Secondary 650's get used for external Video Card power to the 6pin/8pin connectors to the 3rd, 4th and 5th cards (and perhaps additional cooling fans if required in the future).
Can you link to the model cards you are using?
I have been using XFX Blacks and bought several of the HIS when they were on sale on Newegg Business. I have not been able to get them stable at the voltages you are setting with yours. Another poster was able to run his Gigabyte cards with the triple fan setup at .88V. So before I order more cards I like to see the other options.