When you insert a real video card, the onchip video is disabled. Since you are still showing the intel video, it makes me think either the card is not fully seated OR your video card has a problem.
Do the following;
1 Go to the nvidia site and download the latest driver for your card
2 Uninstall any intel video driver. Do not reboot if prompted; just tell it later
3 Shutdown and pull the pw cord from the pw supply
4 Open the case and remove your video card. Note there is a latch that must be depressed to remove the card. Do not just yank it out; you will break something
5 Check the slot with a flashlight and be sure there is noting in the slot. Blow it out with a can of air
6 Install the video card in the pci-e slot and be sure it is fully seated. Make any pw connections as necessary
7 Connect the monitor to the video card and not the onboard port on the motherboard
8 Pw ON. If you do not get a display, something is wrong. Either the card is defective OR the motherboard is defective
9 If you were able to get a display, then install the driver you downloaded in step #1. Reboot when prompted