I have an i3 myself, it's a 4160 @ 3.6ghz mated to 8gb ddr3 ram and a gtx 750(non ti) and BF4 was very playable on ultra with anything from 35-55fps and it played the Battlefront beta with ease also, along with WOWS and WOT.... My computer was a prebuilt and just under £500 brand new from shop and considered a mid gamer, it was a gift and it does everything I want currently, don't own any GTA yet to trial
But I did see better specs for same or less price used or new online(I build computer,s, so always looking) so there are very good options out, but I wouldn't go any lower than an i3, well I would, but not for gaming..