Hybrid graphics switching isn't supported in ubuntu yet. Generally with these systems the HDMI is wired to the nvidia card, not Intel, so it simply won't work. You'd have to blacklist i915 and only run nvidia if you need the hdmi.
** Changed in: xserver-xorg-video-intel (Ubuntu) Status: New => Won't Fix -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xserver-xorg-video-intel in Ubuntu. https://bugs.launchpad.net/bugs/879879 Title: HDMI out not working (Dell XPS L401X) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/879879/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp