There's something wrong with your rig then. I have an i7-860/560ti 448 and average around 70fps with everything maxed in Crysis 2. BF3 multiplayer I play with everything turned down, because I only care about frame rates.
Also, I've seen *plenty* of full-tilt 1.9 Crysis 2 videos on YouTube based around i5-K (either 2500K or 3570K) and single-GPU setups as plebian as HD6770 (the rebadged HD5770 that was replaced by the GCN-based, and cheaper, HD7750/HD7770, who also have their share of C2 show-offage on YouTube).
One other way Crysis 2 and BF3 differ (especially in terms of their YouTube videos) is that typically BF3 videos showcase multiplayer (which can introduce all sorts of outside-the-PC laggage issues into the mix), while Crysis 2 videos showcase the campaign mode - thus, Crysis 2 videos are far easier to compare, even with dissimilar rigs, than those for BF3 (or MW3 for that matter).