Most cards with 2 PCI-E power connectors won't run AT ALL with only 1 connector attached.
I have heard of exceptions, but never SEEN one to date.
The issue with using SATA to power risers is that the PCI-E bus is specified to allow up to 75 watts power draw from the GPU, then the riser ITSELF has to do "voltage conversion" to run that 75 watts from a +12VDC only feed which will eat a few watts as well, while the SATA power connector ITSELF is only rated to provide 54 watts MAX at +12VDC.
There is no way to guarentee how much of it's power a given GPU will draw from the PCI-E power connector(s) and how much it will draw from the bus, so there is a definite risk of overloading that SATA power connector by powering a riser with one.
If the card splits the power draw so that it's pulling less than 50 watts or so from the PCI-E bus then it will work reliably - but there is NO WAY to make the card do that for SURE unless it's a low power card that draws ALL of it's power from the PCI-E bus (most 1050ti and lower) and you turn the total card TDP down to 50 watts or less.
This is not an issue for MOLEX (150+ watt rated power connector) or PCI-E (192+ watt rating on the connector, even though PCI-E spec says 75 they WAY underrate the connector).
I have not worked with Corsair modular power supplies, but most power supply manufacturers design their "peripheral" and "sata" ports on the PS to be interchangeable - might be worth checking to see if you can run Molex from all of those ports on your Corsair.
It definitely works on the Corsair AX860/AX760 but those are Seasonic-built Corsair variants on the Seasonic SS-860/SS-760 models and most Corsair PS models are manufactured by companies other than Seasonic.
Isn't the Zotac 1080 ti Extreme a "8 + 8" powered card?
this is an excellent post // yes it is unless its been changed at some point
