Radeon HD 6870 needs CMOS restart to work

[lsun630]

I recently bought a sapphire radeon hd 6870. when i first intalled it, it didnt work so i resetted CMOS and it worked. but everytime i turn on the computer the card wont work again so i have to restart CMOS again for it to work.
I have installed all the drivers for it.

my computer is a dell xps 71000

 

[clutchc]

Have you changed your CMOS battery? It could be dying and not retaining the settings that default to the new card.