The 750 Ti does not actually come with any authentic Mac yet so enabling its full power is not that easy. The steps to install the drivers are here: NVIDIA Releases Alternate Graphics Drivers for 10.10.1 (343.01.02)
Here are the steps I did:

  • Install NVIDIA Drivers (without card plugged in)
  • Set nvda_drv=1 in org.chameleon.Boot.plist (Extra folder)
  • Shutdown
  • Put in Graphics Card
  • Plug video cable in to the Graphics Card.
  • Enter Bios (Hold down delete key)
  • Disable Intel Graphics
  • Boot Up
  • Check up “About this Mac” or “System Information” to verify that the card is recognized at the right specs
  • To double check, download Unigine Heaven/Valley and benchmark the system.

 

[Success] randomforest's Build: i7-4790k - GA-Z97-UD5H - 16GB RAM - GTX 750 Ti  (Ubuntu 14.04 Dual Boot)-screen-shot-2014-12-26-10.54.44-am.png