I have tried editing both "Config's" in main DIR and saved game DIR and adding an "autoexec.cfg" and have done so years ago for original Doom 3 so know what I am doing.
I can get the console to work but it changes nothing, changing HZ for example does show change in the menu but its still 60hz on monitors OSD and low default RES.
I think the issue is the game does not support my GTX 680 4GB fully (latest Nvidia WHQL driver).
I have the Intel CPU's IGPU disabled in Bios so its not seen or used in Windows.
The only thing I can do is play it windowed and drag it to screen edges.