Need Help With Graphics Card

[calan]

I have a dell dimension 3000 i installed a nvidia fx5500 pci card drivers are working fine. if i disable the onboard and switch my bios from onboard to auto nothing works but the weird part is if i leave the bios on onboard enable the onboard in device manager and set the graphics card as primary display the graphics card works with the monitor. when i reset the computer i don't see anything till the screen that shows the login names comes up i'm not sure if my computer is using the graphics card for games instead of the onboard though even though its the primary display cause both of them are enabled but its the only way i could get the grahpics card to display anything. I have tried all kinds of diff stuff so i figured someone on here might have had same problem and could help. thx