HELP.. no display after replace GPU..

hi.. i just replaced my spare pc with an older gpu(7600gt) i used. but after i replace it the fan on the gpu works and there is heat too. everything is running normally but the problem is that theres no display. my monitor shows a black screen. there is signal but no display.. why? is there a possibility tat the psu is not powerful enough? my psu is 300w.

ya they and from the same company. both nvidia.
how do i even change the settings when theres no display? when i change back to the previous card theres display.

already disabled. its just tat i put in tat gpu no display.. i put back previous got display again.

you said your old gpu had no display
tell me which cards you have and what 1 doesnt work

OK SO PUT THE 1 THAT DOES WORK opps caps and do what i said b4

i supposed u check the cable was connected in right?

ok then so did u check the bios settings? for video display

Same problem here.Recently bought MSI 9500GT MD1G OC/D2.Cards fan is working and everything is normal but monitor goes blank (black) when I start.

This is my card : http://www.msi.com/index.php?func=proddesc&maincat_no=130&cat2_no=136&prod_no=1680