Overview
This little guide aims to provide a final solution to desperate people that tried everything from Windows parameters to NVIDIA ones and still experienced Green Screens (like I did).
Information
4GB Patch is a useful tool that will grant your game the possibility to rely on 4GB of VRAM instead of 2.
As I have browsed many forums in order to fix this problem, many people seemed to think it was some kind of memory shortage, leak or something along those lines so I decided to try this software. If you experience any similar issues with old games that require 2GB of VRAM, I suggest you to apply this patch as well, it will improve the game’s performances and make it more stable overall especially if you decide to use mods.
Software download
1. Download 4GB PATCH[ntcore.com]
2. Extract the .exe
3. Execute the program
Patching the Game
1. When executing the software, this window will pop-up. 
3. Select FFX.exe and execute
4. Voila!