As far as I can tell: adaptability happened.
Look at this shot of the prototype below:

(
from Bitwit's Computex coverage)
The power link is much thinner but also doesn't have the rail system of the finished product. Without the rail, it will only work for cards with two 8-pins and the power sockets in exactly the same spot as the 1080/1070 FTW/Classified.
The bulkier version, however, will work for almost any card (as long as the polarity is the same as on nVidia's reference cards, like on EVGA's cards).