Area 51 upgrade to a GTX 980 Ti need help with power connections

Hi,
I've got an 85 pound Area 51. It too heavy to take to a shop for an upgrade so I will do it myself with help from kind folks on the internet. It has an Intel X58 ATX motherboard with a Nvidia GTX 970. I am wanting to step up and install a EVGA GTX 980 Ti Classified.
I got the 980 installed but I don't know what to do for the power cables/connections.
I'm tryin to figure out what PCI-E power cables to use on a GTX 980 Ti and which one of the two connections on the graphics card to use, or do I use both?
The PSU has two power leads for graphics cards. each one has a 6-pin & a 6+2-pin.
The graphics card has two 8-pin connections.
Do I need to use an 8-pin cable in each one of the two connectors? Or one 6-pin & 6+2-pin? Or just one 8-pin? Or what?
the "user guide" that came with the card is a waste of a good tree.

thank you

 

both 6+2 pin connectors into the card and you're good to go.

 

OK thanks I'll do that.
But what if later on I want to install two GTX 980 Ti cards in SLI? How would I run power to them. I saw another Area 51 same model as mine with two GTX 980 Ti cards in SLI and they had one 8-pin adapter plugged into each card. It was an adapter from the stock 6-pin/6+2-pin PSU lead to 8-pin, one in each card. Was that correctly wired?