I have an AMD Radeon HD 6870 which is shader model 5 and supports directx 11 (I play games in dx11 mode). However, when I select dx11 mode on some image effects (for example, “Depth of Field (Lens Blur, Scatter, DX11)”) I get an error message that says “DX11 mode not supported (need shader model 5)”:
Reasons why it could be not in DX11 mode: 1) You haven’t turned on DX11 in player settings, 2) you’re on Windows XP or Vista without DX11 support, 3) the editor is set to some lower graphics emulation (Edit → Graphics Emulation) mode, 4) something else.
In the editor log file (Console window → Open Editor Log button), at the very start we print out what graphics devices were created, and why DX11 creation failed, for example.