Recent PC build here. I see folks having similar issues but I can't find a resolution. I am running Win8.1. I am having the issue where my ethernet cable is not registering in my newly built PC. It was working fine but now nothing. My modem checks out. Wireless is running fine. I used multiple ethernet cables. CMOS and drivers deleted and installed again. I connected the modem to our laptop. Everything runs fine until I plug in the ethernet to the PC. Please help!