geforce 8400m

I recently purchased a new laptop, i mean brand new, it has bluray and all.

but i had a question with the video. It says its a geforce 8400m 256mb, with 1gb turbocache. What does that mean>>? and in the display properties it says i have 1gb of video and im using 256 of it, how do i use at leaste 512 or alittle more of it.

im pretty sure u can change it in the bios if not it usually changes automaticly

nothing in the bios