My laptop has NVIDIA GeForce GT 630M. After installing Ubuntu, I tried to install graphic driver, NVIDIA X Server Settings, from Software Center. But its reviews are terrible. So I tried to install directly from executable by downloading NVIDIA-Linux-x86_64-340.32.run. Unfortunately it prompts that there is a built-in driver, nouveau kernel driver, which needed to disable. So, I found a way from StackExchange and disable it.
After rebooting, I tried to install that executable again. But it failed as usual and showed a message to go to NVIDIA website and check for solution. As you know, there is nothing except flipping pictures.