I got my Mac Pro refurb yesterday. I booted it up and ran the migration assistant to copy everything over from my Imac. Once everything was done I went to "about this mac" to check everything out. On the display section it shows a ATI 5870. The refurb I bought showed a ATI 5770. Is there any reason why a 5770 would show as a 5870 or did I just get a free bonus?