What Are PCIe and ?

PCIe cards can always operate in PCIe slots with the same or more lanes than the card For example, an x8 card can operate in a slot with x8, x16, or x32 lanes

Intel LGA 2066 ATX motherboard with DDR4 4133MHz, dual and heatsink, , USB Gen 2 connectors, ASMB9-iKVM and ASUS Control Center

pcie x1 in x16 slot ‌PCIe X16 Golden Edge to PCIe X16 Slot Adapter Features : PCIe x16 card edge PCIe x16 slot PCIe Gen 3 16 lanes signals of PCIe designated 4 Layer PCB

pcie 40 gpu in 30 slot That was an issue with older, low-end desktop motherboards having firmware hard-coded to only expect video if the x16 slot is populated,