The ASUS GeForce GTX 780 Ti I've got requires two 8-pin PCI-e connectors but my 800W "90%" efficiency power supply (HP Z620 Workstation) only has two 6-pin PCI-e connectors. The card came with an adapter for two 6-pin to one 8-pin. Would it be enough for me to draw power from one of the SATA power connectors to power the other 8-pin slot?