It says in the guide of your board that if you use a video card in the pcie slot the system will automatically configure itself.
correct what u say Boyet. But I already choose PCIe in BIOS. But after entering the Windows 7. I still saw my Nvidia PCIe graphic card 1024MB RAM with 1024MB Intergrated RAM in system properties. So it become 2048MB RAM. I want to disable the intergrated only.