my laptop is samsung NP670Z5E-X02CN and i just download the mac os Yosemite and successfully installed it， but it don't have wifi driver , what's more the system went slowly. the graphics driver and network can't work. i opened a window , the window taskbar will be Transparent can't see the close and minimum buttom . i wonder if there have graphics driver for Radeon Hd 8870m? ,or it only for HD 7****?