I5 by a long shot. I installed an I5 Ivy bridge 3330 3.0GHz today and it beats my QX6850 core 2 quad 3.0GHz by a long shot in gaming. Core 2 quad was holding my 670 back, but now it's running way faster. So yea, an I series intel chip is faster clock for clock.
Example: Crysis 1 and 2 (the...