NVFlash is the best NVIDIA Firmware Update Utility for updating the BIOS of your Nvidia Graphics Card. Using this tool you can update your VBIOS and can also save the current VBIOS for backup purposes. This is a command-line tool and you can flash multiple graphics cards using this Nvidia GPU BIOS update utility. This tool supports windows operating system and it can also be run from a bootable USB disk.
NiBiTor or NVIDIA BIOS Editor is a utility for editing the BIOS of your graphics card. Using this VBIOS editing utility you can customize or make important changes to your VBIOS file regarding clock speeds, voltage, timings, boot settings, temperature settings and then can save the updated VBIOS to the hard drive for flashing purpose. Now after making the appropriate changes you can use NVFlash to flash your VBIOS using this new VBIOS file that you have saved with NiBiTor. NiBiTor is indeed a very powerful and advanced for VBIOS modding or tuning utility for Nvidia graphics cards.