Would it be possible to BIOS flash GeForce 6800/7800/7900/7950 AGP to FX 5950 Ultra? If yes, would such a Frankenstein work correctly/normally or at least almost correctly/normally?
No, there are major architecture changes between the GeForce FX and 6/7 series. Even then, subtle changes between hardware with the same architecture tends to arise which makes them incompatible with older variants.
VIA C3 Nehemiah 1.2A @ 1.46 GHz | ASUS P2-99 | 256 MB PC133 SDRAM | GeForce3 Ti 200 64 MB | Voodoo2 12 MB | SBLive! | AWE64 | SBPro2 | GUS
No...
But also yes... there's a few lower end models you might be able to flash back and forth since they are essentially the same chip, but need to match exact versions in model ranges that are not often very clear about which silicon they are actually using, examples might be 8400GT/9400GT/210(some versions) and HD5450/HD6450/some R5s. and GT430/GT710 and some others 410-440 and 710-730 they're all over the place. Possibly there might be some matchup in the higher 8x00 series with 9x00s as well. Bottom line is though, you are almost bound to mess up a card. Start with 10 cards that match the parameters of this paragraph, consider it a success if you get 3 working perfectly with an identity switch. Great way to waste a rainy summer when you've got a huge box of junk cards from eBay, not so great if you only have the one and really really need it to work.
Unicorn herding operations are proceeding, but all the totes of hens teeth and barrels of rocking horse poop give them plenty of hiding spots.
You can downgrade 7900/7950 to 7800, I think. No point in doing that though.
I must be some kind of standard: the anonymous gangbanger of the 21st century.
