most ram slots on a motherboard - Why are we putting RAM sticks into 2nd and 4th slot first? download 888 slot

They are often sold in kits of two because most often a motherboard will have two RAM channels which is just a method used to increase performance.

If you are checking a motherboard, it will most likely list the maximum number of memory expansion slots your motherboard has and what type of RAM chips are compatible.

RAM slot, socket, or a memory slot is a gap on your computer’s motherboard where you can insert your RAM. Depending on the motherboard type, there might be up to four memory sockets.