Do MAC graphics cards work in a PC?

In the past I have seen people reflash the gpu bios to work with a MAC - MAC cards are so overpriced. The 680 is a fairly new card - I do not no if there is a flash for MAC using that card - if I see one I post it.
-Bruce
Edit: I see you are going from MAC to PC - sorry not sure if refashing the BIOS will work.