What were the first GPUs to saturate a PCIe x16 slot?

Hi, i recently bought a new computer and plan on getting a new graphics card, but the motherboard has two types of PCIe x16 slots,

Is this also true of all other devices like this? I was assuming they could all reach the 1000mbs that the pcie slot could reach (plus reviews

pciex4 slot PCIe x16 vs Tested in Middle Earth- Shadow of War, Witcher 3, Assassin's Creed

pcieslot PCIe x16, 5 GHz, 16, 1, 8,000 MBs PCIe x1, 8 GHz, 1, 1, 1,000 MBs PCIe If you see that the contacts on a PCI Express x16 slot are reduced to