DirectX 12 just sneaked into Windows 10, but you can't use it yet
SourcePoking around the fresh Windows 10 build last night, I found an interesting new feature that Joe Belfiore didn’t mentioned in his announcement post: DirectX 12 is already baked into the operating system.
Don’t take my word for it! Install the Windows 10 Preview and run dxdiag.exe, then look for the DirectX Version Info at the bottom of the System tab. Boom! DirectX 12.