I don't even know where to begin.
The artificial limits you're talking about to prevent overheating is something the drivers and GPU firmware takes care of. Looking at just framerate when it comes to a graphics card's power output is just plain wrong. It is a combination of graphical detail, resolution, framerate and a bunch of other things. The total amount of processing a card needs to do is what determines how much heat it generates. If I lower my graphics settings so that i'm able to do 120fps, that makes fuck-all of a difference for the graphics card as far as heat generation is concerned.
Quake 3 arena was frame capped because a consistent framerate is desirable for the players, and because at the time the game was released, most computers could not give a consistent 120fps framerate at good graphical settings.
There is no limit in the Q3A graphics engine when it comes to how many frames the game can render per second. I actually downloaded the game just now and did a timedemo with 864 FPS average, and I was CPU limited, not GPU limited. With an i7, I probably would have broken 1000 fps. There is no automatism in high framerate and graphics card overheating. Just because I could, I also tested crysis and got to around 300 fps there, without getting a higher load on my GPU than FF14 gives me at 50fps. Just drop the entire framerate-overheat argument and admit you were wrong.
There is absolutely no hardware-related reason why FF14 can't run at 120fps, or even more.