Even COD was Dx10.. I dont understand what Dx11 does here
Dx11 is compatible with Dx10 card. That's not mean you can play DX10 game with Dx11 functionnality, and specially with a DX10 card.
All it mean is that you can play Dx11 game with a Dx10 card, baut without special effect that are not supporterd by your Dx10 card. Or with DX wrapper, some features can by done by the CPU.
But you must have a Dx11 game (which doesn't exist yeat, of course)!