It's not a competition. Never was. The cpu is the source of fps. The cpu creates all images, instructions, Ai, places objects, dimensions, everything, into a data packet. That data packet is 1 frame. The amount of data packets a cpu can create in 1 second is your fps. The game code and some of the in-game detail settings dictate the level of complexity to the frame, the higher the complexity, the longer the frame takes to put together, the lower the fps.
Those packets get shipped to the gpu, which dissects the first packet in line, creates a wire frame, adds colors, shading, shadows, graphical detail settings etc. Renders that frame according to the resolution. Then puts all that complete image on screen. The amount of times the gpu...