the memory have a profile stored in their stick that can be used by the board to determine the timing for the speed... it's a standard on every rams...
u will only need to manually set timing if using the different set of rams, (when they cannot operate together automatically) or u trying to get better performance by O.C.
Setting manually is not recommended for people who don't O.C..
(unproper set up can lead to rare BSOD)
since timing is not just the 4 digit.. (CL, tRCD, tRP, and tRAS ) there are other will need to be set up .. Twr, Trc, etc...
just setting the 4 digit and let the other auto is only a half done......
please consider any newbie that may read this threat, O.C always came with risk....