Mac Pro 5,1 GPU in PCIe slot 2 - does it

1 slot gpu-APK-IN V gpu slot Graphics cards always go in the highest-up PCIe slot on your motherboard – that's the PCIe x16 slot, the fastest available gpu with m2 slot Slot ➤ motherboardhow-to-check-pci-express-slot ]

gpu blocking pcie slot if the slot is open like that, you should be good to go if it's not open, you could a) use another riser to adapt the x8 to x16, or b)