I think you are right, the NIC ever gets activated, but I don't know enough to find the problem.
In the driver, mtu is set before initialization, as it needs to allocate buffers according to the size.
Then some message about link information should follow, but not found in your log. So I guess that it fails in initialization and terminates itself - that's all I can tell.
This is what I get at the end of the post -
Waiting for DSMOS...
Previous shutdown cause :3
DSMOS has arrived
-->> right here is where the link initializes on the X58A-UD7<<--
Warning: IOPlatformPluginUtil: get CPUIDInfo: this is an unknown cpu -- power management may be incomplete or unsupportd
Sound Assertion in AppleHDACodecGeneris at line 350
and then it blackscreens and the desktop opens up.