Are you using the modified plist hack to enable GPU acceleration? Also, Premiere doesn't use CUDA, it uses OpenCL. At least that's true for CS6.
I used the hack to enable it with my GTX 570 that had in my 2006 Mac Pro without issues and now use it in my Hackintosh and a GTX 970.
Yep, I did the plist hack for Premiere and After Effects back when I was using CC, though the options are still there in CC 2014.
Regarding CUDA, Premiere CC 2014 has a drop-down with both CUDA and Open-CL for their Mercury Engine.