I would go with an EVGA P2 1200 W or 1000 W at minimum for the VGA's That has six PCI-E connectors, six 6+2 cables and two 6-pin pigtail cables. I would use three 8-pin splitters for the double connector cards. Use a second EVGA P2 750W for all six of the risers, motherboard and accessories. That comes with four PCI-E connectors and you can use the two pigtail cables from the 1200 W to power six 6-pin PCI-E risers.
https://www.amazon.com/11-inch-PCI-Express-Female-Splitter-Sleeves/dp/B01LVZBJMLYou could also go with a single EVGA 1600 W G2 or P2. That comes with nine PCI-E connectors and five 6-pin pigtail cables.
