More importantly, what's your GPU usage while you're playing? If you're using Precision or Afterburner, toggle the On-screen display. If you're below 50% GPU usage, your Q6600 is bottlenecking your GTX 480.
I don't want to open up Pandora's Box by stating that a Q6600 can bottleneck a single 480, but that's right, I said it (but of course I have my own personal experience to back up that statement).