> I must admit that this is new to me! I'm not familiar w/ laptops w/ 2 devices like that. Now I > understand why under Windows, Dell has installed both Intel and NVidia software. > Could anyone explain why such hardware configuration? The Intel HD GPU is actually integrated on the CPU die; the discrete graphics adapter usually has higher performance for graphics-intensive applications. In windows, you should be able to choose which graphics adapter an application uses by right-clicking its shortcut and choosing the "Run with graphics processor" option from the context menu (the default can also be set in the NVIDIA Control Panel, with NVIDIA adapters). So you can have the integrated GPU handling mostly static displays and using less battery, while the dedicated GPU kicks in for AutoCAD, video editing, gaming, et cetera. On desktop PCs, if the display/s is/are connected to the discrete GPU's output port/s then the discrete GPU is used for everything. I don't know how to tell which graphics adapter is being used by a particular app in CentOS... the only benchmarking suite I've heard of for CentOS is Phoronix (look in EPEL), which should have the GLMark2 benchmark to test the OpenGL renderers. I'm not aware of any linux flavor that supports Direct3D.