So I have 3x SATA cables/branches with 3x SATA connectors on each. I attached 2x GPUs (which are on 16x USB risers with molex connectors. These risers have molex to sata extenders ) per branch so I dont overload a single branch (3rd SATA connector on each branch is not attached to anything, except one on which I plugged the SSD with nvOC on it). One branch with molex connectors is plugged into the two molex slots on MB.
Alright having 2x per SATA is a good rule thumb. How much power draw per card? And how much from the wall?
2x riser per 1 sata cable can be okay with a 1070 card with a tdp of 150 set to 100
but if you set a 1070 with a tdp of 175 to 125 or more you would be in trouble.
same idea with the 1080 ti the aorus has a tdp of 300 the msi aero has a tdp of 250
if you put 2 aorus set to 200 the sata will melt. and the aorus also drops settings and will go from say 150 to 200
so I would never put aorus 1080 ti's on a sata riser only on a pcie riser using a pcie.