Switch to the discrete Geforce 9600M GT from the 9400M in the 15" 2009 MacBook Pro (MacBookPro 5,3) for better performance

I am using the Nvidia-340 driver and I can’t seem to find a way to use the faster 9600M GT. Graphics performance isn’t bad but playing light games like Minecraft was a much better experience in MacOS. Here’s the output from lspci.

  benji@benji-TuxBookPro:~$ lspci| grep VGA
  02:00.0 VGA compatible controller: NVIDIA Corporation G96CM [GeForce 9600M GT] (rev a1)
  03:00.0 VGA compatible controller: NVIDIA Corporation C79 [GeForce 9400M] (rev b1)