I upgraded from EVGA 780 FTW to EVGA 780 Ti SC a few days ago, noticed that it wasn't compatible so I tried both GraphicsEnabler=No and =Yes.. didn't work. So I tried booting Mavericks with nv_disable=1 and it worked, at first it would only show the desktop in 1024 x 768 resolution. In Multibeast I chose 1080p and it now properly displays Mavericks desktop in 1920 x 1080.. however, I haven't tried anything that would call OpenCL.. and certain things like opening Safari and browsing a site looks a little strange.. It reminds me of when I would do a fresh install of windows without installing video drivers and it would somewhat lag when I would scroll down on a webpage.
Obviously nvidia needs to come out with web drivers for 780 Ti for Mavericks, and/or Apple needs to come out with support, seems very strange that nvidia has been relatively silent on the 780 Ti OS x support, this is nvidia's flagship card. But if you absolutely need to be able to see your desktop then boot Mavericks with flag:
nv_disable=1
It's not perfect but it's better than a black screen