In game, AFAIK, the only way to tell you're in DX12 mode is either some rendering glitches (currently seen on certain Nvidia configurations in my experience), using FRAPS (you won't see FRAPS with DX12), or if you happen to test performance you should see better performance in heavy loads with DX12 (mostly on AMD GPUs). Or just launch via Steam and select DX12 mode.
There has to be a way to do it, but I find it rather silly to have a file called Ashes_DX12.exe launch the DX11 version. Seriously, this didn't happen with an earlier release; why the change? If the GPU can't do DX12, spit out an error rather than just magically launching DX11. I just spent a while looking through the EXE file for a command line parameter to force DX12, but I couldn't find it. Boo! Best guess is it has something to do with the command line p
I know of a few, but it's not clear what several do: -bechmark GDC_Demo (There's an XML file and folder called GDC_Demo -- don't know of any others, but maybe someone could hack the contents and XML to create one.) -max_threads [#] (Minimum is 4 -- anything lower is ignored) -ini_file [filename] (This file should be in your Documents\My Games\Ashes of the Singularity folder) -gpu_profile (Unknown what it does or how to user it) <