PCIe x16 switching to x8 even if no 2nd GPU connected?

Guide to Types of Expansion Slots and Add-In Cards pci e x16 slot An increased number of lanes usually translates to a larger slot So a card that needs PCIe x16 cannot fit into a slot with fewer lanes But a pci slot 1 PCIe is backwards compatible so you can use a PCIe Gen 2 or 3 in a PCIe Gen 1 or whatever combination with little issue The biggest problem you

pciex16 slot configuration PCIe boards can fit into slots designed for their lane configuration or higher Plugging a x4 PCIe into a x16 slot is acceptable