For Bloodhawk, kraxkills, Nico and I, we saw like 10 extra watts on average from the ASUS bios. But generally it just gave us 300-305 watts when measured by our PSU or nvidia command.
Kedarwolf as it seems gets 330 watts, never figured out how or why it's not repeatable for all of us.
But yes, the SC2, Inno3D, MSI and ASUS bios seems to give you 310-315 watts maximum. But you actually don't hit that maximum that often so it'll perform roughly equal to stock (or in my experience worse than stock).
But from my testing, the SC2 bios perform on par with the stock bios with some extra benefits, it is from my understanding a reference designed board after all. You get 0% fan at idle if you want to use that, don't lose a DP1 port.
I'm shunt modded now so I can't measure the wattage of the card with stock settings comparing SC2 and stock bios anymore for you guys. My card will draw 380-400 watts.