Please don't mix and match sticks of ram, you're advised across the forums to buy/invest into a dual channel ram kit that's bundled with two(or 4) sticks of ram, that will both run at the same speeds, frequency and voltage.
Don't do that. IIRC there's no separate overclocking per stick of ram. So one setting might work for one stick and other won't work for the other, thus limiiting the OC potential of one of the stick. Bringing sticks to a shared latency and frequency might also be troublesome.