It's very unusual for network card not to be recognized by nvoc. Not impossible, but unusual.
Since you have extensive Windows experience, have you tried installing Windows on that motherboard to confirm it is not a hardware failure?
If your network card works well under Windows we can rule out defective hardware and try to troubleshoot further.
I have not tried installing Windows. But even if I interrupt the boot sequence and look at the System Information, the MAC address for the LAN controller (which is onboard to the motherboard) is blank. It's like the motherboard doesn't see it. And if I try to plug a USB WiFi adapter in after boot-up, it's dead too. No activity at all. Yet if I plug a USB data stick in to the same USB port, it opens up and lets me browse the stick. Regardless of the OS, wouldn't the fact that the BIOS interrupt and review of system info not showing an active LAN controller indicate it is an issue prior to the OS?
You pretty much answered your question. It seems something is wrong with your motherboard. Have you had the same problem before flashing the new bios? Try downgrading the bios, the latest one might be buggy. If it doesn't help then return or RMA the board while you still have warranty.