To my understanding, RAM should be bought in pairs to allow them to work efficiently, which is why companies have "kits" of 2 ram stick in one package and so on. (Correct me if i'm wrong). What i'm wondering is, do i have to buy a kit that contains 2x4GB (for example i want 8GB of ram) in one package, or is it okay for me to buy 2 of the same 4GB RAM seperately?