I love to get advice from someone who knows the research!
Took your info and found a great page with the specs on most connectors
http://www.playtool.com/pages/psuconnectors/connectors.html.
Looking at the back of the EVGA SuperNova P2 1000w:
https://i.imgur.com/43x131I.jpgEach of the VGA's are 8-pin out (rated at 336 watts per) = so splitting should be 168 watts per split (I called EVGA and they confirmed at least 300 watt per VGA output).
So I'm probably safe on a Y-Splitter keeping less than 160 watts per (and I'm at 126 max).
For the riser you are dead on, SATA is really a bad idea.
That being said, each SATA/PERF port puts out a max 75 watts (interchangeable) so theoretically, each port (4 SATA/2 PERF) 6-pin connector would support a PCI-e riser.
I could get 6-pin to Molex connectors and 'probably' be ok.
The final issue is total wattage, and my question to anyone who knows.
If a card is limited to 126 watts (using SimpleMiner), where does the power for each card come from?
Is it a mix from VGA and the PCI-e riser? Something like 100 watts VGA and 26 watts from PCI-e riser?
Or, is the power to the card considered from the VGA connector, and they PCI-e is separate power.
If they are separate, then I'm doomed with a 1kw PSU.
That would be 780 watts (230x6) for VGA + 450 watts (75x6).
Can anyone confirm if the total GPU card power is split between the PCI-e and VGA, or are they unique and separate?