ram slots 2 and 4 not working

ASUS M4N68T AM3 AMD motherboard DDR3 4 RAM Slots + CPU + Cooler - £31.59. FOR SALE! Fully working bundle. It has four ram slots.

Regarding the RAM type, i.e., DDR 2, DDR 3, and DDR 4, a motherboard is NOT backward compatible. You cannot install DDR4 RAM on a motherboard that supports DDR3 RAM and vice versa.

Similarly, obtain a working RAM and try it on all the slots to see if your PC responds well to it. If the RAM does not work at all or functions in only some slots, then the problem may be in the memory slot.