No I downloaded his users manual. There is no BIOS setting to disable the onboard VGA, and no jumper setting as well.
DD Here is what I want you to try. First of all remove your graphics card.
Then go to nVidia's site and on the drivers download page download the 6.6.9.3 driver. I know there are newer ones, but those drivers will work best for that card. I know I have a 5900GT and I benchmark higher with those than the 71's or the new 75's. You'll find them in the archive section. A link will be on the left side of the drivers page. Anyway save them to your hard drive.
You need to go into the add remove programs window and see if the VGA Driver is listed. If it is uninstall it. If it isn't don't worry about it. Go into the device manager and open the display adapter. You should see your onboard VGA listed. Double click on it and go to the driver tab. Hit uninstall. A message will ask if you really want to uninstall this device. Say yes. Then you will get a message saying you have to reboot to complete the installation Do you wanna do it now? SAY NO. Then shut down your system. Don't restart, shut down. Unplug the rig and install the video card. Plug it back in reboot and go into the BIOS.
Go to Advanced Chipset Features, AGP timings and set the aperture to the size of the memory on the card, and the transfer mode to 8X if it's an 8X AGP card. Then go to Integrated Peripherals, and set the Init Display First setting to AGP. I think that's everything for now. Hit F10. It will ask if you want to save and exit? Say Y. When it reboots you can use the new hardware wizard, but I always just install from the executable where I saved the nVidia drivers. Those little tool tip balloons will pop up in the lower right corner. Be ready with your mouse and X out of them, and cancel the found new hardware wizard. You will get a balloon saying there was a problem with your hardware and it may not be installed properly. That's a good thing. That's what we want to see. That means the vga is running off the default MS drivers. Go to where you saved the drivers and start the install. When it's done it will ask you to reboot. Go ahead and when it boots back up everything will be really big. That means it's working. Right click on a blank spot on your desktop hit properties, go to settings, advanced button and adjust your resolutions and stuff.
OK if you want to overclock your card, then go to
http://downloads.guru3d.com/download.php?det=815
and download ForceWare Coolbits 2.0 That will unlock your frequency settings on the nVidia tab in system settings. Have fun. I hope this works or I'll be P.O.'d. That was a lot of writing for my hunt and peck style LOL Let us know if you got it up and running. Good luck.