What is your cpu? Some of the AMDs don't like odd timings. Try a 10,10,10,24. Beyond that RAM is a finicky overclock sometimes. Your clock is where it is because that is where corsair set the SPD which is kind of a guaranteed safe clock. Regardless of the memory sometimes the motherboard simply cannot handle it and every stick varies somewhat on what it can actually do which is why SPD is typically less than advertised clocks on high end RAM. XMP isn't something that "works" it is more of a built in overclock profile. So if the module isn't able to take it or your motherboard isn't there turning on XMP isn't much different than setting up your timings and clock to an unstable level. Also mix and matching sticks with RAM overclocks is setting yourself up for disappointment. It is also important to understand that sometimes with RAM overclocking it may have no real performance gain if you have to mess with timings too hard. Those numbers are in essence delays counted in clock cycles. So if you are having to up the delay by two clock cycles to stabilize the system you are losing ~20% to gain ~20% clock frequency for no net gain and increased power consumption while you have to up your voltage. Serious overclockers will often buy multiple sets of memory and test out each stick and bin the best performing together but they are all going to be the same. If you have two different version numbers on your sticks they are not the same and performance could be all over the place.