With an unflashed 980 you have to remove the card with every OS and Web Driver update before it will work again.
As I just verified, our EFI card will allow basic screen function on one display, letting you install and choose web driver. This is currently impossible without EFI on 980.
So for the CP shills, there is a "functional improvement".
This is actually a pretty big benefit.
And for sake of clarity, vast majority of the 10 initial shipping units are the ACX Dual fan version. Only 2 people got Reference cards. They both have separate advantages. Reference exhausts heat outside case, so you don't double handle the heat. On the other hand, the ACX cards do an amazing thing, for most desktop use THE FAN REMAINS OFF. In fact, I can start the Uningine Valley Extreme HD benchmark and the fans remain motionless for upwards of 60 seconds. The old Fermi cards (470/570/480/580) would have already shut the computer down due to overheating, the Maxwell card is that much more efficient.
So the ACX cards can be quiet at idle and standard web surfing. Keep in mind that this magic means that the MP PCIE fan is doing the work, so it may go slightly higher. But watching the ACX fans sitting still while rendering Valley is magical.
Very proud of our work, and thanks again to Nvidia for continuing to support us Mac users.