Pick i3,Z170 mobo and High speed RAM like 3000+ Mhz ,cuz that will help i3 in CPU heavy games.Later in year or so you can sell i3 and get i5 or i7 if you want more performance out of your PC and you feel need for it.Fine Z170 mobo is MSI Z170-A PRO.It supports RAM speed up to 3200Mhz and it wont break your wallet.