ATI RADEON graphic card problem

my graphic card RADEON 4670 was dead.

I have sold a new graphic card on internet (ref 661 - 5539), the seller said it's compatible with imac late 2009.

i install it inside and my screen stay black. the imac boots but only my external monitor is working (my sreen is working with old graphic card).

can i solve the problem or i must purchase the 661 - 5308 ? (the good part i think).

on information system, il see that number of ROM and EFI are different.

thank you for your help

Rodolphe