I think ive found the system specs needed to run IL-2 CloD perfectly

[skouras]

with the GTX 580 1.5 Vram i've got no problem on very high and high settings
i'm running on 1920-1080 LG monitor
so its enough for me
you will need the 3 Vram version if you want to run the games on higher resolution but this isn't the case with COD here,as i see people here complain that the sim eats above 1.7 Vram
conclusion'----the game needs optimisation ASAP