MOBO and GPU compatibility warning One additional PCIe x16 slot

What is the purpose of having more than 1 PCIe x16 slots? pcle x16 slot PCIe x16 Gen expansion backplane with two slots The PCIe x16 Gen3 backplane has two PCI Express x16 slots, with one slot supporting the OSS target pcle x1 slot AMD B550 Ultra Durable Motherboard with Digital VRM Solution, PCIe x16 Slot PCIe x16 slot with faster bandwidth and lower impedance 2 PCIe

pcle slot The 'x16′ indicates the maximum number of PCI Express lanes supported and thus, the length of the slot As version , each lane provides