Will the new "Graphics Driver" (Directx 12 with Windows 10) works with the Hardware Supported Directx version (Directx 11.1) "Graphics Card"??
Yes. Actually, Direct3D capabilities are advertised by driver to apps as "feature level", so app written to Directx12 API will use available feature level for rendering, in case of Haswell it is D3D_FEATURE_LEVEL_11_1.
Will the new graphics driver support my graphics card??