barto :
To add on to what shatter said, I'm assuming that you have your monitor connected to the 660 and not the motherboard, correct?
Do you play any other games? If so, what frames per settings do you get from them?
You may be right, if hes using the motherboard the game would run off integrated.
@OP If you are using the motherboard HDMI port go into your bios, you should see something about the main video output, you need to switch it to PEG or whatever your motherboard calls it. After you switch it save and turn off your PC. Switch the cable to the GPU and it will now run everything off the gpu by default.