I am using 2x Corsair RM1000X on both of mine 6 vega rigs.
Nothing special about how to manage the cables - PSU 1 powers CPU, 2 molex to the MOBO, 3 Vega and 3 different Sata cables to the v007 risers. PSU2 - powers 3 VEGA, 3 Risers (SATA) and the SSD.
The good thing about the corsairs is, that the PSU comes with 4x 8pin+ 6+2 pin cables, so if you wish you can power 4 vega cards without any extenders.
How long are you running those rigs?
What's the total wattage of your rig?
The first one - since ~15.09. The second is fresh. Drawing around 1100W from the wall last I checked.