this is how switchable GPUs work... when the game is launched the hardware monitors how much resources is being used and then chooses which GPU is best for that task. the beta was not perfect and the launch of the game as had a few updates so the engine is probably running better since the beta so the game is not using has much resources. the end result is your hardware thinks it only needs to use the intel GPU vs GTX650. intel 4000 is a very decent GPU.