Hi looking to upgrade my memory I have a Asus H110M-E with i5 7400 but only one ddr4 8gb 2133 should I stick with the same and add another 8gb 2133 or go to 1 or 2, 2400 16gb sticks (what eva I can afford at time) or run the 8gb 2133 with a 16gb 2400 and when can afford second 16gb stick replace the 8gb I believe that will work but will only run at lower speed? All advice welcome