Can you explain the different versions of PCIe ?

Any other pci slots occupied, have you checked pcie x16 bifurcation settings and pcie config gen 1 gen 2 gen 3 in the bios of the motherboard

PCIE 1x, 4x, 8x, 16x bus pins and signals Pinouts > Computer buses and slots connectors · 36 pin PCI-Express x1 connector layout

pcie 50 slot Simplifies system design and time-to-market Part Number Channels Pin Config I2C Config Package Contact Pitch PCIe Retimers 89HT0808P

pcie gpu slot With full backward compatibility, PCIe provides the same topologies and channel reach for client and server configurations as in PCIe