Nope. PCIe lanes are not shared. There are some chips (and a lot of motherboards) that allow (or automatically perform) remapping of lanes, though. That's wh

Nope. PCIe lanes are not shared. There are some chips (and a lot of motherboards) that allow (or automatically perform) remapping of lanes, though. That's why if you check a motherboard with SLI/Crossfire, it usually has some setting in the BIOS to either dedicate all 16 lanes to 1 PCIe 16x slot or split 2 PCIe 16x slots 8 and 8. The chip has to be removed.