Today I purged bumblebee and installed nvidia-prime again and found the solution. The key is DO NOT REBOOT after changing video card in nvidia-settings. If you want to reboot right after the change, you MUST LOGOUT AND LOGIN then reboot, or, at least on my laptop, the discrete card will disappear from lspci and cannot be switched. Purging nvidia-prime and a shutdown will recover the discrete card.
nvidia-prime 0.6.2 Ubuntu 14.04 kernel 3.13-0-24-generic nvidia-331 331.38-0ubuntu7 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1310023 Title: 14.04: Nvidia Prime is unable to switch to the Nvidia card To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/nvidia-prime/+bug/1310023/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
