converting nVIDIA TNT2 / TNT2 Vanta into TNT2 Ultra / TNT2 M64
Unlike with the GeForce chip nVIDIA has implemented no featuresets in the TNT2 chip. The TNT 2 family consists of NV5 chips with the following names: NV5, NVUltra, NVVanta and NV5M64.
The difference between NV5 / NVVanta and NVUltra / NV5M64 is just the core frequency and bus width. Although you can modify the ID of the chip it won't give you any utility.
The selection of the PCI ID can be done by setting voltage levels of the BIOS chip on the graphics card. The procedure is mostly the same on all nVIDIA based cards because almost all manufacturers use the reference design by nVIDIA. You only have to adjust two 10kOhm resistors on the board.
see also: converting GeForce into Quadro
always connected to ground
remains unchanged for TNT2 cards