Strange looking shadows

I am not sure if this is a bug, hw problem or just the way engine handles shadows, but for some  time I can see somewhat strange looking shadows on objects. Graphics card is Nvidia Geforce 750 Ti

 

Screenshots with examples attached.

post-247735-0-17288400-1427837667.jpg

post-247735-0-86350300-1427837674.jpg

post-247735-0-92644100-1427837694.jpg

Yeah it’s just a rendering thing around the fringes of shadows or where the shading is very thin

It is known trouble. Thanks.