Help with PSU connectors for my hd7970

Hey guys. I just bought an hd7970 and tried to hook it up (it has 1x6 pin and 1x8 pin), but I can't get my computer to boot past the motherboard screen.

I have an Antec TruePower 650w. What I've tried using is the cable that comes from my psu and ends in a 6+2 pin and a 6 pin (same single cable). I also have those red 8 pin jacks and black 6pin jacks in the psu itself which I'm guessing I should use? Sorry, I'm new at this.

Thanks a bunch for help.

What is the exact model number of the power supply. I'm seeing 3 different models online. Your power supply should have 2 or more of the 6+2 connectors, you need to use them. Not sure what you mean by red 8 pin and black 6 pin jacks. The only full 8 pin connector you have should be for the motherboard cpu connection.