There should be a 4+4 pin connector and a 24 pin connector which go into the motherboard. The GPU will then require 2x 6 pin PCI-E power cables. (assuming you purchases the one mentioned above)
Don't plug a PCI-E cable into the 12v ATX 8 pin socket. Different connectors for different things, don't want to cause anything to blow up.
Don't plug a PCI-E cable into the 12v ATX 8 pin socket. Different connectors for different things, don't want to cause anything to blow up.

