X.M.P or manual settings for F3-12800CL9Q-16GBSR1 with asus sabertooth z77?

[idahludbA]

system spec: i5 3570k - 4x4 F3-12800CL9Q-16GBSR1 - asus sabertooth z77
this is my first build and i'm not familiar with a lot of terms and do not know what to set them as.
I want to overclock my cpu and ram, what should i set the ai tuner to? X.M.P or manual?
at auto memory modules work at 1600mhz 11-11-11-27.
When i switch to X.M.P memory modules work at 1600mhz 9-9-9-24 1.35v as advertised, do i keep it at this sitting? or change to manual? (i read that manual is better than X.M.P)
can i overclock ram to 1800-1866mhz or more with same advertised timing and volt? or should i change them?
sorry for asking alot of questions, i'm new to this stuff and thank you in advance.

[Tradesman]

With 1600, it's 6 of one half dozen of the other, either way should be fine, XMP will run the sticks as advertised, if you want to play with the timings or OC the sticks, go manual. The DRAM is independent of the CPU so it won't affect a CPU OC