Sounds like it's working! Do you maybe have Green LAN enabled in the BIOS, if so disable it and see if this helps. Also remove any Gigabyte power saving programs you may have installed, just in case.
If you continue to have issues, try clearing the CMOS fully by removing the power supply cables from the board, or unplug it from the wall. Then remove the CMOS batter, and press and hold the case/motherboard power on button for 1 minute. Then put the battery back in, and connect or turn on the power supply, then bootup and enter the BIOS and ensure Onboard H/W LAN is enabled in the Integrated Peripherals BIOS page, and disable Green LAN
If that does not help, and you are not already using the latest BIOS, please update via Qflash or DOS, then load optimized defaults and save/apply/reboot back to the BIOS and ensure LAN is enabled, then test in the OS again