Share memory on MSI Z77MA-G45 an 3570k

Hi all,

I have a MSI Z77MA-G45 mobo and a i5-3570k CPU. I use the integrated graphics.
On the mobo's spec page says that the maximum share memory is 1760MB. I can only set 256MB in the BIOS. Is there something else that I need to change to get more mem...