Thanks for the extra information.
As mentioned above, mixing individual memory modules is risky, the modules may not be necessarily compatible with each other.
Here are some suggested compatible 2 x 8 GB dual channel kits to consider instead -
Corsair, part number CMY16GX3M2A1600C9
Corsair, part number CML16GX3M2A1600C9
Corsair, part number CMV16GX3M2A1333C9
Corsair, part number CMY16GX3M2A1600C9R
Corsair, part number CML16GX3M2A1600C10
Corsair, part number CMZ16GX3M2A1600C10B
Corsair, part number CMZ16GX3M2A1600C10
Corsair, part number CMX16GX3M2A1600C11
Corsair, part number CMX16GX3M2A1333C9
Corsair, part number CMY16GX3M2A1600C9B
Crucial, part number CT2K102464BD160B
Kingston, part number KVR13N9K2/16