This has been said before, but I'll repeat it just in case - all TNT2 cards (sans the M64) use the same core. Some will have "PRO" or "Ultra" stamped on the chip, but not all (my MSI TNT2 pro does not but it's detected as PRO and runs at the correct frequencies). What lets the driver discriminate between cards is the device ID witch is written in the card's BIOS:
0x0028, 0x0000, "RIVA TNT2/TNT2 Pro", "RIVA TNT2/TNT2 Pro"
0x0029, 0x0000, "RIVA TNT2 Ultra", "RIVA TNT2 Ultra" }
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This doesn't really impact performance, since the card is still physically a Ultra (if it's clocked faster then a PRO card and uses memory faster then 166mhz). It's entirely possible your card uses the 0x0028 tnt 2 PRO device ID - this should not impact performance. If you want the card to be displayed as an ultra in device manager, dump the video bios with gpu-z, grab NIBITOR (nvidia bios editor) and change the deviceID, then flash the modded bios with nvflash. The modification is cosmetic only - it does not bring any performance advantage unless you up the clocks. Most TNT2 cards can do 140-145 (PRO clocks) - some can even do 160 (I have a prolink tnt2 that does). GPU clock seems to be more influenced by how new the chip is and how much power it's getting. Back in the day I managed to push my sister's TNT2 M64 to 160mhz just by replacing some 40k resistor on the back of the card near the GPU with a 20k - that made it A LOT hotter but I installed a socket 7 heatsink with a 60mm fan on it and it worked for a while.