For a long time, AMD and Intel were locked in fierce battle, producing faster and faster CPUs - and when they finally hit the wall and could no longer bump up the GHz, they started gluing together multiple cores for more processing power. The manufacturers have done it at such a pace that, these days, the CPU is becoming less and less important in gaming. You get the same real world gaming performance with a $150 part as with the $1000 part unless you have a very high end video card to go with it, and even then the differences are minor.