In my first reply, I wrote:
Don't skimp on cables. Don't use a 6/8pin GPU power adapter from SATA or Molex. Even 2xMolex to PCIE isn't a smart idea.
To which you replied:
This rig has individual PCIE cables for each GPU and riser. Sorry but I fail to understand which cable is wrong.
And then, a few posts later, you post links to
6 Pin PCI to SATA Power Cable with the question of whether to use them or not?
I really don't know what you don't understand here.