On AMD 7870, 16.12.2
It seams this is reproducible on Win 10 so there could be some issue with WDDM 2.0 and older GCN1 cards.
1. Go to File->User Preferences-System - Check OpenCl, save user settings
2. Click Emulate Numpad , save settings and close window
3. Press number 0 on numpad (you will go to camera view)
4.Switch to Cycles and device GPU compute. Set tile size to 512x512 under Performance.
5. Go to create tab -> Plane, radius 50
6. Right click on cube -> Click ROUND ICON, Click New material
7. Render the scene, wait while scene is rendered
8. Go to this tab and click 3D view
9. Go to this tab, click on it and click Rendered (wait while kernels are loaded )
10. Go to the same tab again and click Solid (wait while kernels are loaded )
11.Go to material tab of the cube from step 6. and change roughness of material
12. Repeat step 9. and 10.
13. Click render again, click Window -> Toggle system console