I am building a pc and have
decided each component except the GPU. Now I am looking for a really good gaming GPU for the price.. So what is best nvidia gtx GPU for gaming that will be within a 400-500 price range?
Can you post the rest of your rig? We need to know which power supply you´ve got, as the video cards are dependent on PSU wattage. Also tell which is your CPU, so that we can recommend a card that won´t bottleneck your CPU.
Anyway, assuming that all is OK with your rig, then at that price range the best you can get is a GTX 670, as suggested by sarinaide.
Don't skimp by getting a Reference model because they used sub par components and often wimpy coolers. Go for MSI or Asus due to better cooling design and higher grade build quality.