sorry, I have a funny Problem -> can't find a way to attach the file to the ticket :/
So, here is the content of the config file, pasted into this note. i am actually using Settings as suggested by Arma3 (Autodetect).
steamLanguage="German";
language="German";
forcedAdapterId=-1;
detectedAdapterId=0;
detectedAdapterVendorId=4098;
detectedAdapterDeviceId=37984;
detectedAdapterSubSysId=-518711477;
detectedAdapterRevision=0;
detectedAdapterBenchmark=124;
displayMode=0;
winX=96;
winY=35;
winWidth=1776;
winHeight=1000;
winDefWidth=1024;
winDefHeight=768;
fullScreenWidth=1920;
fullScreenHeight=1080;
refresh=60;
renderWidth=1920;
renderHeight=1080;
multiSampleCount=4;
multiSampleQuality=0;
particlesQuality=1;
GPU_MaxFramesAhead=1000;
GPU_DetectedFramesAhead=0;
HDRPrecision=16;
vsync=1;
AToC=15;
cloudsQuality=2;
pipQuality=3;
dynamicLightsQuality=2;
PPAA=1;
ppSSAO=1;
ppCaustics=1;
tripleBuffering=0;
serverLongitude=11.5833;
serverLatitude=48.150002;
ppBloom=1;
ppRotBlur=1;
ppRadialBlur=1;
ppDOF=1;