XPS 8700, Nvidia video card upgrade

Hello All!

I have a Dell XPS 8700 desktop and am hoping someone here can guide me as to what Nvdia graphics card is compatible with my tower. I don't know what kind of PSU or what kind of connections are required to handle a higher powered card. For the longest time I didn't even think it was possible until I saw these forums. I mainly want to play a game called Final Fantasy 15 on from Steam on high settings. I have attached some photos of my current system. Any advice is greatly appreciated.