A:Answer you always want to use the same size of sticks in each slot if you have multiple sticks inside your computer. If there are already 2 RAM sticks in there, you can replace those two with two new ones that are double the size and you will double your amount of RAM. There is nothing magical about ones sold as sets, other than they are usually cheaper in sets of two, and if you have (2) slots, you would want to use the same size of RAM sticks in each slot.