How to Check PCI Express Slot Version? - PC Guide 101
Image: Different form factors follow a different PCIe slot configuration.
Plugin Parameters - Application SDK - Global Site
This configuration has the advantage of implementing two-way SLI, while only occupying one PCI Express slot and (usually) two expansion I/O slots.
1 Port PCI-e to 4X PCI Slot Expansion Enclosure - Coolgear
PCI-e 4X PCI slot expansion box is designed to expand from an existing PCI Express slot on your computer system. The PCI Slots are plug and play expansion.