I don't think I have ANY 6pin / that the problem. I have sata 6-pin with four flat sata connectors on one string and then perif 6-pin with 4 molex string.
No 6-pin to 6-pin cables. This is the problem.
Okay, there's a terminology problem here.
When we say 6-pin or 8-pin, we mean the 6/8 pin
PCI-E power cables. EVGA G2 750w has four.
Basically, you could use a 8pin PCI-E splitter and connect it to both the RX GPU and direct to the riser's 6 pin socket.
Alternately, it's possible to get (or make) cables that convert the PSU's second CPU EPS12V 8pin connector into a pair of 6/8pin PCI-E and use them to power a pair of risers.
Example:
http://www.ebay.com/itm/CPU-8Pin-to-Graphics-Video-Card-Double-PCI-E-PCIe-Power-Supply-Splitter-Cable-/272720358725Or.... for the risers with the direct molex connection, you could obtain more EVGA G2 compatible molex cables, as for an EVGA G2 all the SATA/PERF sockets on the back of PSU are wired identical/interchangable. (EVGA G2, G1 and GS all use the same pinout for the molex cable)