Any combo deal that comes with predetermained parts to save you money will not be good to OC
at most, get a barebones of the cpu and mobo you want. then buy Corsair ram, a good cooler, a Corsair PSU and a good GPU
and your set
as for Overclockability MSI has a nice feature in their Bios that helps you get started with overclocking so i would recomend MSI as a starterboard. then Buy a Asus when your ready for an upgrade.