Would connecting a PCIe GPU to a PCIe port affect

EZDIY-FAB Vertical PCIe GPU Mount Bracket Graphic Card pcie 4 0 gpu in 3 0 slot The old games are going well - Mafia 3 for example I found a correlation that if the game load GPU is around 60-70%, there is no problem with pcie gen 4 in gen 3 slot Feturing with Gen4 riser cable, supports PCIE ,Compatible with RTX3090, RTX3080, RTX3070, RTX3060TI, RX6900XT, RX6800 See all features

pcie 20 x1 slot As Zef said, PCI-e is backwards compatible You can put a PCI-e GPU into a slot or a PCI-e GPU into a slot, it'll just run