UEFI booting with Sapphire R9 270X Toxic gpu?

[Leatherskull]

Can someone please clarify how I would use a Sapphire R9 270X Toxic gpu with my Maximus V Formula mother board. I use the UEFI MB bios on my system, and Sapphire claims:
"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"

Does this mean that every boot will require a slow legacy bios boot to use the gpu and then I have to hit the Sapphire button to be able to use my UEFI bios normally? Or do I just set the Sapphire button to UEFI once and it stays that way......allowing me to boot my machine to the UEFI MB bios, but always in the slow legacy bios speed?? I am totally confused about this.
Any clarification on this would be very well appreciated! Thanks
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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 * Blu Ray Burner ASUS BW-12B1ST *

[Praz]

Hello

I would think pressing the button once would lock in UFI mode but this would better be answered by contacting Sapphire support.