I have an Asus z170 Gaming Pro board which came with an 8GB Corsaire Vengeance DDR4 2666 mhz stick. Today I bought a Hypertec DDR4 8GB 2133 Mhz stick to go with it on the recommendation of a Maplin assistant who said it would be fine and the board would just lower the speed of the 2666 to match the 2133. Before I install the 2nd stick in my machine, is this a good idea or should I return it to the store? Am I putting my PC at risk by mixing the two?