Windows 7 PC with added graphics card, unable to see on-board graphics

I have a new Windows 7 (64) PC which has built-in graphics on its (MSI H61M-P31/W8 (MS-7788)) motherboard. I have also added an NVIDIA GeForce 8500 GT graphics card, which is working fine, driving two monitors.

Now I wish to have a third monitor attached to the motherboard graphics, but it appears that my system doesn't know of the existence of the motherboard graphics. If I look at "Display Adapters" in Device Manager, I only see the NVIDIA card. What have I done wrong?

EDIT: There was a similar question on SU here, but the accepted answer did not indicate exactly what to do to make it work, i.e., no mention of BIOS settings.

Solution 1:

Most motherboards do not allow you to use both the on-board graphics chip and an installed card. It's usually one or the other, with very few exceptions that I've found. In order to add additional monitors, you'll have to add another graphics card.

Your motherboard's manual doesn't state specifically one way or the other, but you can try an experiment. Go into your BIOS settings and look for graphics settings. In the settings, make sure the on-board graphics are enabled, then save your settings and reboot. Make sure you have a monitor attached to the onboard output. In all likelihood, only the on board graphics will now work and nothing will show on the monitors attached to your NVIDIA card. If all three screens show up, then congrats it worked! Otherwise, go back and disable the on-board graphics. You'll have to wait until you can add a second graphics card.

Solution 2:

First make sure you actually HAVE on-board graphics.
Even though the connector is on the motherboard the actual IGP (Integrated Graphics Processor) is build inside the processor. You will need to check if your CPU actually has one. Not all Intel CPU's do. It depends on the model-number of the CPU. You can use a utility like CPU-Z to check what exact variant of CPU you have.

Second the motherboard must support using the IGP and the GeForce in parallel. If it doesn't you are out of luck.
If it does, you will most likely have to enable that feature in the Bios first.
If is usually set to "Use PCIe, fall back to IGP". This needs to be changed to "Use IGP + PCIe".
(That's most likely not the exact text. How the setting is called in your Bios I don't know.)