some intel hd gpus have a limit, and no matter how much more ram you put you cant go over that limit, now am not sure about what i just said but i used to have an intel hd 2000, it had 512mb vram and i had 2gb ram, later i upgraded to 4gb so my vram was 800mb or something, i upgraded again to 6gb ram but the 800mb vram didnt change so i thought maybe the 800 is the limit