My PSU has two extra GPU 2 pin connectors

Hi there!

First of all, this is a great site and I finally registered! I have found many helpful hints and tricks here!

I recently bought myself a Gigabyte GTX970 G1 GPU, now it has an 8pin and 6pin acquirement. My 800W PSU has two 6pin connectors, with an extra 2pin ,ps_7 and ps_8, connector connected to the cable. Now I assume that is for upgrading to 8pin. But I am not sure as to where or how to plug them in or which one, 7 or 8? Has anyone ever heard of this before?

Thanks do much