It's generally not as simple as one purely outperforming the other. At low level, there are probably some instructions that take fewer cycles on one, but other instructions that take fewer cycles on the other. Thus it depends on subtle details of how a program (game or not) is written and compiled to determine whether it performs better with an Intel cpu or and AMD cpu. Also, most games become less affected by the cpu as the resolution goes up, so at 2560x1440, some games might be less than 1 fps apart between using an Intel or AMD cpu. I play Skyrim, which has been shown to favor Intel cpus (even at 2560x1440), but I can easily believe there are other games that favor AMD cpus.