gaming video memory

[Tobster57]

I've just bought assassins creed syn and this is the first high-end game I've got for my pc I got back in august. But when I play the game the graphics are really bad so I go to change them, but in the menu it says I cant play higher than low-quality because when I play it on low it uses 1800/750 mB of video memory. But I've checked and I've got 4 gB of video memory so why is it not working?

 

[fictionyuuka]

Pls post the specs of your computer so we can have a better point of view of your problem