I am down to a choice between GTX 860m 4GB - with i5 (lenovo Y70-70) or GTX 860m 2GB with i7 (Asus G751) - both systems have 8GB RAM and 1960 x 1080 screens. Which would be better for games such as Witcher 3, Project Cars, F1 2015? What is more important more Vram (2GB vs 4GB) or better...