How to transfer system RAM to video card RAM?

Hello I have 1GB of system RAM. I would like to transfer 256MB of it to my video card. Is this possible? I've heard other people done this. How do you do it?|||If you have an onboard video card, you can do that through the BIOS. If you have a separate video card that can use shared RAM, you need to check that card's documentation.|||This can only be done if the video card is onboard and it is done in BIOS.