On a motherboard spec, what does the x8 mean in 1 x PCIe x16

On a motherboard spec, what does the x8 mean in 1 x PCIe x16 pcie 8x slot Now, I read somewhere that if you use the top slot, you're giving up 8 PCI lanes shared with the top PCI-E slot So my 4080 would be running pcie 4 m2 in pcie 3 slot If it's an 'open-ended' PCIe slot with say 76 connectors in the 'major' half but will still

pcie 4 m2 in pcie 3 slot I have an old motherboard which has a x1 PCIe and one x16 PCIe slot I need to split the x16 slot into two half-height x8 slots,

pcie 20 x16 slot The PCIe x8 Gen3 backplane supports a PCIe Gen3 target cable adapter installed in the OSS target slot and up to one or more PCIe x16 expansion cards The PCIe Gen 3 Switch allows users to take advantage of a single PCIe x8 slot, through the use of QIP2X-PCIE8XG302, and transform their PCIe