Probably a dumb question but any of these should work with my EVGA SuperNOVA 750 B1 Power Supply correct? 3x 8pin (6+2) for PCIE connectors.
Should be fine on the PSU.
Grab a GTX 970 for ~300-330$. They're some of the best price-to-performance cards out there right now, and they will fully support DirectX 12 when it comes out. Which is shaping up to be a big deal.