DDR4 vs DDR5 with 13900k

DDR5 RAM on AM5 fails to POST with all 4 slots occupied ddr4 in ddr5 slot The pin layout is different between DDR4 and DDR5 This means it's not physically possible to install DDR5 RAM sticks in a DDR4 laptop or vice ddr4 vs ddr5 slot DDR4 is not backward-compatible with DDR3 so a DDR4 DIMM will not fit on a DDR3 DIMM slot Not only is the key notch of each DDR generation

ddr4 and ddr5 same slot DDR5 32GB 6000MTs · Explore Form Factor Platform Application 11 x PCIe Slot Reinforced PCIe x 16 2PCIe Ready PCB Low signal