I assume you tried it in another machine?

Nup but identical card works fine.. As do many others

Toyed with flashing bios but not that optimistic.. Perhaps rubbing eraser on contacts is possible but spitting out random chars in bios screens (in bios config menu also) seems too much like something has failed - ram?, ramdac?

Cool to see it did keep up at 100MHz bus speed. Weird how some V3s can do this while others stop at 80MHz or so.

I doubt a higher bus speed could fry the RAM or DAC, these always run at 143/166/183 MHz generated by the gpu.
Maybe the gpu just overheated? Thermal stress breaking the solder joints? In that case you could try pouring some solder flux under the BGA and baking it for a few minutes at about 200°C.

Voodoo 3's do run very hot so def a possibility - it's in the sad bin of somewhat faulty parts atm. Cool suggestion tho - will prob give it a shot before giving up completely.

Actually a lot of the older era cards radiate quite a bit of heat.. Esp wavetable daughterboards!

Ps: I am running pc150 ram so maybe that is what let me boot when normally you'd get a black screen?

Wait, you mentioned getting random characters across the screen. I got this too once, when I tried running RAM at CL 2 instead of 3. That would make RAM a more likely suspect I guess.
Also, did it fail while playing Quake, or only after a reboot?

After a reboot it started doing that - makes it into windows (just) then locks up.
I resetted all bios settings to fail safe before giving up and swapping the card

I did a memtest just then with no problems.

Can never rule out weird cap related mischief or general board flakiness though (Abit BF-6), But the problem completely goes away with a different card so I'd say it has to be the video card.

Might take some pics/vids next time I get the card out. Interesting to see if anyone has experienced anything like it with other AGP cards.

There is one more thing you could try.
Run the V3 as a secondary VGA (using primary PCI VGA) preferably in windows XP. XP should detect it and install drivers. Then you can try to extend the desktop to the V3 (with second monitor connected, of course)... and see if there are artifacts or not.

If there are no artifacts, then the Voodoo3 chip and memory are both fine. Most likely the video BIOS is corrupted and/or the flash chip is damaged. I have experienced this once on my 3dfx Banshee - somehow the BIOS chip got damaged and the card would not boot at all. Simple reflashing didn't work, so I had to desolder the damaged BIOS and replace it with a new one. After this the Banshee is working once again just fine.