|That should be the setting, if it does not let you, try shutting down and swapping the memory in the slots. Some motherboards go by the memory in the first slot for its settings and if they are different enough, one may not run at the others settings. Also look at the labels on the memory and see that they have the same detailed specs, memory with the same speed ratings may be set to run at different latencies due to batch or quality control. As mentioned, purchasing memory in matched pairs is important. If switching them does not work, it is possible to play with the memory settings manually, but you may consider the possibility of returning both of them and purchasing a matched pair.|
I am running four sticks from two matched pairs, but I researched the memory's details before purchasing the second pair so I could still run them at their max specs together. Even then, CPUz shows that one pair has 3 possible settings and the other pair has 4 possible settings (one a true overclock setting), but they all run at the same setting which was important to me then and now without having to experiment with the manual settings to get them to work together.
Also note that on many motherboards with four slots, dual channel memory does not always go into neighboring slots, many use slot 1 & 3 as a pair and 2 & 4 as a pair so make sure that they are on the same channel (pair).
You have to be a little bit crazy to keep you from going insane.