Alpha's are just that alphas. They don't run final versions so the hardware demand for the alpha should be taken as a grain of salt. For example, BC2's Alpha and Beta only ran in DX9. Once the game was released, DX10 and DX11 were implemented. So you can get a false system requirements from early versions of a game. Like I said, until the final version is released, when benchmarks and reviews are done, then you will know just how taxing a game will be on hardware.