ADLINK VPX3000 - Manual (Page 46)

34 Board Interfaces
4.6 Switches
PCI Express to P1 Configuration Switch (SW)
This switch sets the PCI Express Lane configuration at the P1
connector.
Mode 1 2 3 4
8x PCIe x1 OFF ON OFF ON
1x PCIe x4 + 4x PCIe x1 OFF ON ON OFF
2x PCIe x4 (default) OFF ON ON ON
PCIe x8 ON OFF OFF OFF