i have also got the same card. And done some volt modding to it. Even some more, rather interesting tweakings.
But what you are talking is not possible my friend.
There is nothing to unlock in FX5700Le card.
And dont try flashing 5700 ultra's bios into your card!
But if you want to then flashing with Quadro's bios of 1100 would be much better to mod it to extreme.Still there are not any perfect setups like this.But you can atleast try this if you want to.
Again,this is really dangerous, you can simply end up with nothing but a wasted card.
Still you want to do this.....?ok?
try installing Nibitor from softpedia.com or guru3d.com.
You can scrap two of your registors if you want to, using NvStrap and its antiprotection patches.
but you have to back up your cards bios first on a different pci card, so that in case of emergencies, you can always revert back to the original settings.