i5 2500K has only 4 cores but is very optimized, specially for games. The AMD's 8120 has 8 cores and it will run better when using applications that can handle well these 8 cores. Gamers choose i5 2500K because you don't see games using more than 2-4 cores (maybe this will change in the future). Though, for video editing and other multimedia applications (PS etc.) AMD's 8120 should function better because, in general, such top applications are using more cores than top games.