Review on 🎮 PCI Express Video Card Power Adapter Cable for Mac Pro Tower and Power Mac G5 with Dual Mini 6 Pin to 8 Pin (38cm) by Bob Kussmaul

Thankfully you won't have to change it once it works, but on the first attempts at installation the cord connectors snapped into place but there was no power - because the connection was the metal -to-metal in the connector not actually touched. Pushing and pulling the connector several times solved the problem, but is not necessary.