Because PCs, when properly programmed, simply don't exhibit the mythical inherent huge performance penalty compared to consoles. We see this time and time again.
It's not surprising. AMD's DX11 driver CPU overhead is significantly higher than NVs.I'm surprised i3/750ti does better than the i3/280 at times in the benchmark video
https://www.youtube.com/watch?v=9pxeF08qmtg