As said above, if a GPU is installed, onboard graphics will be disabled. You could take out the GPU if you want to test with the onboard. Even if using the GPU, you may need another monitor to configure the HDMI output. When I first connected my TV Via HDMI, the TV was not displaying anything because the GPU was outputting a signal at a resolution the TV couldn't handle. Of course, I had my OS installed so I could install the NVIDEA control panel software to make the changes.