I was struggling for the longest time to get the GPU given to me by my friend Tommi to work with Premiere (to use the GPU for playback rendering), and here’s how I finally managed to get it to work:
Go to the Premiere folder in Program Files, edit the cuda_supported_cards.txt to include the card (make sure it is a CUDA-supported card), and add your card if it ain’t there. In my case, I futzed around putting in GTX 560 until I used the GPUsniffer.exe in the Premiere dir and found that the actual name of the card was GTX 560 Ti.
Also, needed to go into the NVIDIA control panel and change the multiple monitor settings under Premier Pro.exe to “compatibility” mode. (And make sure CUDA was turned on there. It was.)
As always, writing this down so that I don’t forget this if I have to rebuild this machine at some point.