Question : Problem: Setting up dual Monitors

I have an HP computer that we just bought. I want to setup for dual monitors.  The computer came with a onboard video card, and we purchased a NVidia 8400 video card.  The problem is when trying to setup up for dual montors the computer is only seeing one monitor (the pci e nvidia card).  I went in the bios and changed the onboard card to the default video card but it does will not recoginise the other card.  Both montiors work but I just can not seem to make them work together.  

Answer : Problem: Setting up dual Monitors

Usually you cant use this configuration, meaning add-on card and on-board card at the same time on any desktop computer cause both graphics cards utilize some system resources in common, which causes system conflicts
So since your NVidia graphics card has only one monitor output i would suggest that you leave it as is with one monitor