I found my Blender can't display metal material correctly, so I tried to open a new clear project and just create a pure monkey and a metal material to it, the material only be modified the color to C0C0C0,Metallic to 1 and Roughness to 0. the result shows like below and this is not expected!! Does anyone know what's the problem??? 
I have light in the scene( just create a new project with basic settings, one light and one camera) and from the metal preview it shows the same result.
The weird thing is I found if unchecked "Scene World" then it looks better in viewport preview but no help for render.. why??

