Make sure that the bios is set to use the PCI-e slot on the motherboard so that the on board gpu in the processor is not the only one being used.
That would certainly cause the new vga card not to be detected.
Other things to try.
1: reseat the card in the slot, on occasion being too far into a slot can also mean a bad connection
2: Use up to date drivers from Nvidia's website, not the ones that came in the box as they will be VERY old.
3: try the card in another machine to confirm it is not faulty.
Also try not to repost the same question multiple times