Windows 10 x64 home, Nvidia GTX 1070 with latest WHQL drivers.
Short description of error
Some kind of normal maps - like folded foil or crumpled sheet of metal - produces black artifacts in their folds with "Glossy BSDF" shader node (no problems with
"Diffuse BSDF" though). That start to happen then "Strength" parameter of "Normal map" node is high enough - at low values (~"0.5" and lower) those black artifacts disappears.
Exact steps for others to reproduce the error
- Open attached scene
- Switch viewport to "Rendering" mode.
[[ http://www.techkind.org/Blender/[Bugreport]%20Normal%20map%20artifacts.png | Example screenshot ]].