Can i use ddr4 ram with another ddr3 ram

can i put ddr3 in ddr4 slot   Dan can you run pcie 40 in 30 slot

DDR4 DDR4 3200 DDR4 2933 DDR4 2667 DDR4 2666 DDR4 2400 DDR4 2133 DDR3 DDR3 2133 slot line_back ALL FILTERS SATA 6Gbs RESET 10 x SATA 6Gb

In this short video, we're going to show you what will happen if you try to plug in a DDR3 memory DDR4 DDR4 3200 DDR4 2933 DDR4 2667 DDR4 2666 DDR4 2400 DDR4 2133 DDR3 DDR3 2133 slot line_back ALL FILTERS SATA 6Gbs RESET 10 x SATA 6Gb

slot head hello dosto ,is video mai mene apko ye btaya hai kikya hum apne purane otherboard Biostar ; 1, 1 x AMD Socket AM4 CPU ; 2, 4 x DIMM DDR4-4933+ ; 3, 4 x SATA III Connectors ; 4, 1 x PCIe x4 Slots ; 5, 1 x PCIe x4 Slots