If not limited by the cpu or a frame limiter/vsync the gpu will render as many frames as it can (i.e. work as hard as it can).
If I have vsync turned on in the game settings then GPU will provide as much fps as my monitor can output and not more?
I want to buy a really good GPU but I don't want it to give me more than 75 FPS. I rather have it running on easy mode.