I've got my V770U for a long time, but I've never successfully flashed my GFX card's BIOS, at least not with any nvflash.exe. Ha! I'm sure it's not the problem of BIOS ROMs. Someone help!!! And I also noticed V770U used a V770 BIOS image, although the EClk/MClk is 150/183 and BIOS said it's "Ultra". They sure changed that in BIOS. I guess it's not a standed way of doing it. This cause problem when u instll in the reference driver, V770U was recongized as TNT2/TNT2 Pro!!! It's just annoying everytime u do it even though it's no big deal.
I currently have a diamond Viper V770 ultra in my posesion, and I have had no such problems whatsoever. Even though it was used on 3 different motherboards (Intel D815eea, MSI 6117, FIC PA-2013).
What programs are you using that recognize it at the wrong chipset? Operating system? Drivers Version? If you have already flashed (or tried to flash) the BIOS of the card, you may have done it succesfully, but the program you are using didn't bother to recheck what videocard you had when it started up again.
P.S. That card is quite overclockable. I have mine running at 175 core, 222 mem. I added a slightly larger heatsink to the core, and put the stock hsf on the other side, with some thermal pads, but the mem has no cooling whatsoever. It is rated at 5.5ns, which means its good up to 200mhz.