Alright, I checked the graphic settings and activated vsync.
Sadly it also did not help. I still need to change the resolution in d3d9.ini manually to even start the game and the UI is still 4:3 while the game is 16:9.
But I found that when not using fullscreen it seems to work without editing d3d9.ini. I would be ok with windowed, but sadly the window resolution was 1024x768
I only have the main mod enabled and it works, as soon as I add the widescreen mod it can not initalize the 3d engine unless I edit the file.
Generic Mod Enabler - v2.6.0.157
[E:\SilentHunter3\MODS]
_LSH3-2015___FULLVERSION
_LSH3-2015_GUI__WIDESCREEN