Not sure what this supposed to be.

The plastic extender looks a lot like the one on the HD5770 that came with my 2010 MacPro so it could be from a 2006 MacPro as these had an X1900XT as an option.
The gamer looks on the shroud on the other hand speak more for normal PC card.

(edith: some search results indicate that this indeed a genuine MacPro (1.1/2.1) card)

Flashing might be an option, or just running 2 cards connected to 1 monitor (which might/should autoswitch to the active input).

[ Edited by Kronos 24.05.2024 - 16:30 ]