Moving this discussion to the Hardware forum.
Big Jefe what version of Premiere are you referencing? Also which operating system are you using?
I assume you mean the hardware acceleration is not selectable? What version of Premiere do you have?
As well as needing to know your PPro version, what is your nVidia driver version?
Right click in any open area of the Windows desktop
Select NVIDIA Control Panel from the popup window
Select SYSTEM INFORMATION at the lower left corner
Driver version should be the 1st line in Details
I have a GTX285 using driver 296.10 and Win7
I just experienced this same issue today after replacing my Quadro 2000 with a Quadro K2000. I found a text file in Program Files/Adobe/Abode Premier Pro CS5.5 called cuda_supported_cards.txt. I bought CS5.5 quite a while ago (before the K cards came out), so they aren't on the list in this file. I added Quadro K2000 to the list, saved the file, restarted PrPro and I now have Mercury Playback GPU Acceleration with the K2000.
I tried that. the card shows up as active in the general tab but the performance was not there.
I went in to regedit and deleted the S.I.D. for the log -in profile.
The machine is working now.
i don't know why this works but it does.