I own a 2010 Mac Pro, and I would like to upgrade the 5770 card to some other. As I read here, 7970 needs more juice than mobo can actually provide, but what about 7870? Will it work? Does it need some hacking (flashing, etc.)?
No drivers yet. The MP can handle this card. You could always use it in windows only but it will be hard to know when you hit the boot screen to switch over.
It should work under windows but not in OSX due to lack of drivers. You can put your 5770 in slot 2 and switch power leads and switch screen connector when want to be in OSX.