hi guys im thinking of adding a second card to add to my 8800 gtx , now i dont know much about adding a second card as i have not had more than one before but i do know that my system will take it as ive got more than enough power at 1100 watts and enough pci express leads and room on my 680isli board. do i need to have a second 8800 gtx card or could i add a newer card like a 9800 gtx ? as a rule do you have to have the same card ?