MVKTech has just posted an extensive Guide on the NVIDIA BIOS Editor (NiBiTor).
"This tool is designed for advanced users only! NiBiTor (NVIDIA BIOS Editor) is the original and definitive BIOS tweaker that supports the latest NVIDIA cards. NiBiTor allows graphics card enthusiasts to have full control over advanced features and functionality found on firmware on supporting graphics cards. NiBiTor, offers the latest in uber tweaking, gaining full control over the latest releases of supported GPU's. The latest release allows full manipulation over the Geometric Delta clocks of the latest video card technology found on supporting cards. All this info is about the current version of NiBiTor (namely NiBiTor v2.3 - 17 July 05)." Read more at MKV Tech.