No Video

I have a Dimension 4500 that i am looking at for a friend. There is no video at from the PC the screen is black. it never gets any signal al all from the pc. I replaced the original video card with a NVidia GeForce 5200 with no luck. Is there any thing that needs to be reset in CMOS when a card is swaped? The pc will power on and fans come on on the power supply. I did try replacing the power supply with a spare i had and still nothing. Cn anyone shed some light on this for me? Thanks