I am thinking in buying the GF 680GTX 4gb to use it with Premiere Pro CS6, but I've just discovered it's not compatible as a GPU Accelerator. Is there any way I can make it work with the program? Thanks in advance!
Yes... I run one and it works fine.
How To Enable GPU Cuda in Adobe CS6 for Windows
It is both compatible and supported in CS6.03. It is compatible with earlier versions, but not officially supported.