7800gs oc video issues

[drums101]

ok so i have a 7800gs oc that i know works cuz it was in another pc and worked fine so its not the card..but when i try to put it into another pc a Dell Optiplex gx260 it doesnt output any video...The fan spins up and it seems like its working but it doesnt put out video..if it makes any difference i used to have a 6200le in that pc that worked fine..when i put the oem card back in the pc works fine so its not the card thats broke or the mobo but its the commmunication between the two..anyone have any ideas on whats wrong?? any suggestions will be appreciated! Thanks

 

[drums101]

forgot to mention that the bios is set to agp slot as primary video not integrated so thats not its