If you lived down the road I'd say pop over to me cave, I have a few dozen motherboards hiding around here somewhere.
The smbios method as far as I was aware was only ever done with controller cards, didn't think it would apply to 10G nics too, so interesting to hear it actually somewhat posts albeit freezes.
Yes, try the firmware, you're on the right course, at this stage I do not believe there is any known issue with these cards, could simply be an incompatibility with your particular model of motherboard or maybe even the bios revision of the motherboard, you could always contact Asus via the appropriate channel.
If you are able to try it in another workstation/desktop board, and you get the same issue, then you could quite possibly have discovered an issue with this model of nic. In which case you go down in history for being the first 'Googlable case' right here at STH.
Personally I tend to avoid Broadcom for NICs, ever since their vmq issues back in the days I just been 'off' them completely. Sometimes it pays dividends to just dig a little deeper for the extra few pennies to put towards an Intel card