Re: How to identify faulty NIC Card in Ubuntu?
The fastest test I can think of, assuming you have a known-good Live CD (or Live USB stick) of some OS, is to boot that instead of the installed OS. Two different Live CDs would be even better. For example, if networking doesn't work with a recent Parted Magic or Ubuntu Live CD or USB stick, then I would declare it "broken".
Another approach, if someone has a wifi USB dongle available, is to try networking wirelessly. If wireless works, but ethernet doesn't, then the ethernet transceiver is probably broken.
Intel Core i7-950 / Asus P6X58D-E / Nvidia GTX480 / siduction 64-bit on OCZ Revodrive SSD / KDE4.10.2/ Kubuntu 13.04