Hello all, I have been through a bunch of solutions and I must contribute what worked for me:
First of all I would like to point you to this thread as a way to troubleshoot your Realtek Ethernet Port going into deep sleep mode. Comb through this thread ( http://answers.microsoft.com/en-us/windows/forum/windows_7-networking/realtek-network-controller-not-found-if-deep-sleep/799d8e2c-416e-4d5a-b56a-1e85f2c3263f
) and try the following:
-Unplugging the power supply for 30 minutes
-Removing the CMOS battery for 30 minutes
-Removing my RAM for 30 minutes (Separately and with the CMOS battery)
-Reinstalling/Repairing the driver
-Resetting bios settings to default
If your controller still isn't showing up in device manager at all we will move to the next step, which is updating your bios completely.
If this doesn't solve the issue try a fresh install of windows and at that point it may be acceptable to give up hope.
After trying all of these and more I ended up driving 3 hours to where I purchased the motherboard and swapping it out and it fixed all of my issues.
RIGHT AWAY I WENT INTO DEVICE MANAGER AND STOPPED THE SLEEP FUNCTIONALITY. That is crucial!!!! I can't stress it enough. Apparently windows can ruin this part of your motherboard and burn out the chip via faulty drivers and sleep initiation.
I hope your troubleshooting has more results than my experience!