SATA 15pin to 8 pin pci cable
Eliminating the need to upgrade the power supply for the sake of video card compatibility. Expertly designed and constructed of top quality materials, this SATA to PCI Express Video Card Power Adapter Cable is flexible.
It is an absolutely functional set of wires and connectors. It will plug into the the things it's meant to plug into.
Bought this to power a new video card that required an 8 pin power connector. The power supply I have is more than enough to power your card, and it did come with an 8-pin connector in amongst the modular cables.
The cables that you did have installed, you had plenty of free SATA ports, and this adapted two of those into an 8-pin connector. It works, and that's all you could've asked for.