What i did with my 470, i just "merged" 2 cables in the middle.
So generally you have black wires and yellow wires going from one end to the other.
I i did cut one extra cable up and soldered 3 ends again together and
got one cable with extra power output.
Now i still have 2 gpu ports on motherboard but one splits half in the other end
and powers my 4000 and second slot for 470.
--
Margus
http://iconstudios.eu