You Need To Know About DDR3 and DDR4 Memory

ddr4 in ddr3 slot   Dan ddr4 vs ddr5 slot

But the default specification says i have 4gb ddr3 l memory so now which is best for 2nd ram slot ddr4-2400 or lpddr3-2133? 0

No, you can't use DDR3 on a board that has DDR4 memory slots only They won't fit and won't work  No They don't even fit in the same slots There were a very few motherboards that had DDR4 and DDR3 slots, but you could only use one

catch 22 slot I explain the physical differences between DDR3 & DDR4 and some of the differences between Vamos a explicarte cómo saber cuánta memoria RAM tienes y de qué tipo es, para que puedas saber si tienes DDR3, DDR4 o cualquier otro