Yeah, there should be an 8-pin connector somewhere in there, it may be hidden behind the other side of the computer depending on how well they were at cable management. Usually it is close to the 6-pin connector though.
it has 2 extra 6 prongs attached to each other with a 2 prong also connected to those wires. the video card now has an extra 6 and 2 hanging off with on six attached. the 680 card came with a converter I believe to make 1 8 out of 6's correct?