‎Memory RAM Slot B seens to not be working!

Physical Differences: DDR5 and DDR4 RAM sticks have different notches or key positions This means a DDR5 RAM stick won't fit into a DDR4 slot

The targeted memory speed is not guaranteed when DIMMs of different part numbers are connected within the same channel When mixed DIMMs

ddr4 in ddr3 slot No, this implies DDR4 and DDR5 are not the same and there are no different RAM slots on a motherboard

ddr4 vs ddr5 slot DDR5 RAM offers higher data transfer rates compared to DDR4, resulting in improved performance The increased bandwidth allows for faster