Most powerful card requiring 2 6 pn connectors?

[bamj6]

I currently have a 5770 in my rig as I downgraded from Twin Froz 560ti since last posting 2 years ago. I will get a 6970 as a christmas upgrade since my brother got a r9 295 x2. He's planning to give his old crossfire 7970 to his other older brother leaving 2 6950's modded to 6970's. I'm taking one as my mobo can't crossfire.

But is that the most powerful 2 6 pin card? Or just the best on AMD's end.

 

[clutchc]

The best 2 x 6 pin card would probably be the Nvidia GTX 970. I don't think AMD can touch it w/o going to 6+2 pin.