For brand specific:
The vgabios will allow you to test it first without writing it.
nvflash will allow you to write it. Use a DOS bootable disk and copy the utility on there. Copy the firmware to another disk if it's too big to fit on the same one.
The file for your 5950U BFG card Rev 2 is here:
I recommend doing the brand specific one first. The generic will sometimes disable your fan speed modulation and power management stuff, but it's model specific, so you have to read up.