MSI Z87 XPower -- Aux PCI Power Connector?

[Phyltre]

I'm currently setting up/cable managing an MSI Z87 XPower motherboard and I'm seeing an "auxiliary" six-pin PCI express power connector between the CPU and PCI-E slots. Checked the documentation and a few reviews of the board, don't see it mentioned anywhere--what does it do or help? Does it just supply more power to the PCI-E ports if needed? Is it necessary? Can anyone find any actual documentation about it? This is the first motherboard I've seen with this additional connector. I only ask because it's going to be a huge pain to properly route a connection to it cleanly.

Visible here on the left:
http://www.hardocp.com/image.html?image=MTM3NTg3OTY4NGR1WWJqcWJ3TDZfMV8xOV9sLmpwZw==

Maybe I just haven't happened to get one that had this before and they're really common now, I don't know.