GPU renders look different than CPU renders

After installing a fresh copy of Windows 8 , I realized that Blender had a problem . When using CPU rendering the image looks like this :

And when using the GPU rendering it looks like this :

The number of samplings doesn’t matter , the difference will still be there no matter the number

I am using a dell Inspiron 5545(laptop) with these specs :
CPU : AMD Quad-Core A10-7300 1.9 Ghz
GPU :AMD Radeon R6 Graphics 2 GB

I have all drivers updated


have you tried rendering the scene instead of the viewport
Are you using any features that are not currently supported by OpenCL rendering ?