>
> If something which used to probe as
>
> ex0 at pci2 dev 12 function 0: 3Com 3c905C-TX 10/100 Ethernet with mngmt (rev. 0x78)
>
> now probes as
>
> 3Com product 0x0000 (ethernet network, revision 0x78) at pci2 dev 12 function 0 not configured
>
> after a dead graphics card was replaced, i.e., reads 0 instead of
> 0x9200, does it mean it is dead, or is there some hope for it?
>
or your PCI bus is problematic. try this card in another machine.

it's strange for 2 different cards to break similar way.