You should almost always be significantly less concerned with what the BIOS says and far more concerned with what the OS says. The BIOS basically just initializes the hardware, and after that the OS tends to bypass it as much as possible for various reasons.
it shows intel graphics 4000 and not the mentioned nvidia geforce gt 640m card[/quote/]
You either bought a v3-571 laptop (without the "g") they use intel HD instead of nivida. Or some one sold you a non "g" v3 either on purpose or by accident (they are about 150-200 bucks cheaper). OR you haven't activated, or put the computer into performance mode. Go down to the tool bar and click on the the arrow pointing up, which is on the far right. And click on the nivida green eye, if there is no green eye then you don't have a "g"..., but if there is and you clicked on it max out the card or personalize it and open up all of the ram.
But I'm pretty sure you have a non "g"... I wrote the other stuff in there to help others out with performance problems
i own a v3571g, i'm writing this on it now and the position of the mouse is really annoying... anyways, My little sticker thing says mine only has 1gb dedicated to the nivida... If anyone knows how to chang it let me know its an "acer aspire v3-571g-6407"