I have been trying to set up two monitors to my computer; after finding that I cannot hook up one to the VGA connected to the motherboard and the other to the VGA connected to the graphics card I then purchased a $40 DVI-D cable so that I could just plug in both to the mother board. Neither monitor displayed. Tried rebooting, again nothing. Tried just plugging in my original monitor, original VGA to the motherboard VGA as I had it before, nothing. Hooked it up to the graphics card, voila, it works... only one problem there are not two ports on my graphics card, therefor how do I get my computer to output through the motherboard again rather than the graphics card?
If the previous suggestion doesn't work, try shutting off the PC and removing the graphics card, boot up without it, and the PC should go to motherboard graphics, then shut down again and put it back in. Some PC's switch over to discrete when you hook up to it, and don't have an easy way to switch back.