Can I Use DDR5 Graphics Card On DDR4 Motherboard -

No, this implies DDR4 and DDR5 are not the same and there are no different RAM slots on a motherboard

Bought a MSI Z790 Edge d4 board and some ddr4 memory While at Microcenter I had them test my ddr5 ram

ddr4 slot In past DDR gens , servers handled UDIMMs and RDIMMs interchangeably In DDR5, they're not compatible; RDIMMs and UDIMMs are no

ddr4 in ddr5 slot If it has a DDR4 slot, you can use DDR4 RAM If it has a DDR5 slot, you can use DDR5 RAM You cannot mix different types of RAM on the same