Hi Folks ...
I would like to use a Sapphire R9 270x Toxic gpu on my Maximus V Formula mother board.

The Sapphire documentation says:
"Dual BIOS ( Legacy and UEFI ) Support
This product supports both Legacy and UEFI BIOS. By factory default, the card itself is under Legacy mode.
By pressing the button with SAPPHIRE logo, UEFI mode will be easily enabled."

I am confused by this. Does it mean that if the UEFI button is engaged that the card will then work correctly with my UEFI
bios enabled...
or
Do I have to set my MB bios to "enable both legacy & UEFI" boot
or
Does this all just mean that I will not be able to use the fast boot function of UEFI bios but all the rest of the UEFI settings are fine...
or
any combination of the above?

Sorry for being so thick headed about this but I sure would appreciate some specific info on this situation. Have asked Sapphire about it and cannot understand what they are telling me...including them saying my current Sapphire card does not support UEFI bios but I have been using it for 2 years with my Maximus running UEFI
Win7 64 Ultimate
Any advice on this will be most greatly appreciated!!

************
RIG to date:
* Thermaltake Level 10 GT case * Cool Power Gamer 980 watts * Maximus V Formula *
* Intel i7 3770k cpu * Corsair H100i * Corsair Vengeance 16GB [2x8] 1600 *
* Sapphire HD6870 gpu * OS Win7 64 Ultimate * Monitor - LG 42LK520 LCD TV *
* SSD [OS] OCZ Vertex 4 256GB * Data HDs: SG 3TB, WD 1TB, WD 500GB, WD 500GB *
* Webcam Logitech C920 * BluRay Burner ASUS BW-12B1ST *