1) be sure all connections are connected and not lose. this includes the monitor cord at both ends, The card in the pci slot. any other connections to the new card.
2) let us know what card it is and if it is a used card or new.

if it an old pci or a new pcie type (be sure the slot is right for the card)
3) do you get any thing on the monitor like a blink or ?
4) did you fell that kinda snap when placing it in the slot?
5) also what were you using before in the system? (if it was onboard you may have to disable it first)
most of my display card problems with new cards were something was not plugged in right.
I know its a pain. just went thru a bad display card myself not to long ago..
give us a shout back an maybe we can help..