I am about to buy:
Asrock z77 Extreme 4 Motherboard
core i5 3570K
This motherboard is said to support upto 2800Mhz (OC) and this CPU supports 1600Mhz or DDR3 according to intel.
With no experience in OverClocking PCs.
For Rams I am not sure what will happen if I put more than 1600Mhz. Eg I want to get 1866Mhz or 2000Mhz for future proof . Will the Rams clock be automatically reduced to 1600Mhz unless I overclock. Or will I have stability issue?
Yes, it will work fine. I run 2133 with mine. It will by default just run at 1600 and you can change it if you want to. Though there doesn't seem to be much point unless you are doing some memory specific task. In games I only bench marked near 0-4% difference going from 1600 - 2133 . . . probably within my margin of error.