Is DDR4 RAM compatible in a DDR3 RAM slot?

You Need To Know About DDR3 and DDR4 Memory ddr3 vs ddr4 slot DDR4 SDRAM : DDR4 SDRAM provides the lower operating voltage and higher transfer rate The transfer rate of DDR4 is 2133~ ddr3 slot -73% Ant Value B450MAD4-N Motherboard Socket 11553rd and 2nd Generation Core Series CPUDDR3 1333MHz

ddr3 in ddr4 slot No, you can't use DDR3 on a board that has DDR4 memory slots only They won't fit and won't work