Dual 8 to 8 Graphics Power Cable Compatible 030-0571-000 K80 M60 M40 P100 Professional Graphics Card GPU Cable

Also doublecheck the power cable. Mine just got here and it came with a GPU to PCIe Riser power 8-pin so I'm trying to find the right power combination of Square and not square that fits both the card AND my PSU - I found another reddit post that says we need this converter