On most motherboards there's a small (green or orange or so) LED near the Ethernet port to show there is connection. Does that light up?
Maybe something is damaged. Maybe the cable isn't well connected? Does it work if you use it if you connect a laptop in stead of your PC?
I've had my pc for a while now which i've bought from someone else. The problem is that my ethernet connection wont work where i've plugged the cable in from my pc to my router and it says that there is no ethernet detected. All i can say is that the problem started after i installed a new graphics card. If someone could help that would greatly appreciated.

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