PCI E Question and Issue

[Gentroce]

So I bought a gtx 970 today and noticed it has 2 6pin connects on it. I currently have a 

BFG 550w ATX Black Power Supply

 

My issue is, while opening and removing my old temporary graphics card I noticed I am missing a pci-e cable that came with my psu. 

The psu is semi modular and I didnt need the other pci-e cable at the time of use.

While removing the old graphics card I noticed the pci-e cable i did have is 8pin to 6pin but 2 of the holes on the 8pin side that go into the psu are just hollow

.

 

My question is, can i buy a second cable like this, plug it into my psu, and plug both of these into my gtx 970 to power it? 

 

Why are there the 2 hollow holes on the 8pin side of this cable? Is it so i can use a 8pin to 8pin if i want and/or a 8pin hole to 6pin if i want?

 

If my description is to weird ill try to describe what i mean a little better.

 

 

[Gentroce]

any idea on what kind of pci-e cable i could get, would a 6+2 to 6 work?

[Aniallation]

You can use a dual molex to 6 pin adapter. I'd still suggest upgrading that PSU though, it's not a great quality model.