Ohh, I don't know. I'm not sure they would have designed it with that in mind. Apparently the PCI-e bus is rated for up to 75W on the x16 bus, but the 1x link is rated for 25W.

Since it's only one plug, it should only in theory be able to supply another 25W. Certainly not enough for 6 non powered risers. Maybe it could provide a full 75W, or three risers worth, but it is missing 15 lanes of grounds.

I wouldn't advise it, not for 6. Maybe two or three at the most.