I'm not entirely sure if what I have experienced in the past is what you're experiencing here, but from what I know, enabling MSAA through your video driver causes this kind of stuff.
I'm using an Nvidia card, and through Nvidia Inspector, I changed the "Antialiasing Compatability" mode to 0x20000000 for Silent Hunter III. This alone has essentially fixed all of the strange artifacts and lighting glitches I was getting.
Not sure if this will help, or if you're even using some form of Antialiasing in your game, but if you are, try it out. Hopefully AMD cards have some sort of similar function in their drivers, but I wouldn't know
