U sure nforce3 MB can't use Opteron??!!
My last MB is Epox-9NDA3+(Nforce 3 Ultra)
It's BIOS can reconize Opteron 144 modle correctly.
in advance,I could overclock to 2.7G(9X300 in 1.45V)
So I think if Socket 939 MB can use Opteron or not.
It depends on BIOS. Not like U say all nforce3 MB could't use Opteron~