If the game itself doesn't limit the frame rate, then speeding up the CPU might help. Even today, Higher clocks will outweigh more cores for a lot of games. Depending on how OLD you mean, most games don't benefit from more cores at all past 2. Stuff like emulators, games through the early 2000's like Core speed more than core count. the 670 will go as fast as the CPU can feed it data, up to (the GPU's) limits of course.
Ther than that go into the game and disable vsync if you have it on, but this might cause graphical glitches, so you'll just have to see.