it depends on how heavy your gaming is, if it's just light(ish) gaming like some MMORPGs or LoL or indie or older AAA titles, then an i3 is definitely enough.
and how high of quality do you want your gaming to be, if it's just medium/high settings on bioshock infinite, tomb raider, or something similar at a reasonable resolution, then an i3 paired up with a decent graphics card will be good enough, you won't be running BF4 multiplayer Ultra or anything, but you won't really have any troubles.