XS_SHOW_SHADOW_FOR_PERSPECTIVE_IN_DX
Category in Advanced options dialog box: Model views
Use this advanced option to control whether shadows are shown in the DirectX rendered model views when the perspective projection is on. Shadows are more noticeable in the perspective projection than in the orthogonal projection.
By default, this advanced option is set to TRUE.
If you change the value, you need to reopen the view to activate the new value.