Broadband :: New PC's Internet Access Won't Work?

I have two PCs with the same problem. The ethernet port on the motherboard does not recognize an Internet connection. I'm running Win 7 64 bit Pro on both. My older PC needs to have the enternet cable disconnected before Windows boots, then once the OS is all booted, I plug the ethernet cable back in and I get an internet connection. On my new PC, I had to go into Device Manager and delete the ethernet card ( not the drivers) then reboot. Windows then recognized the card and connection and the Internet works. What is causing this? One PC is an Intel I-7 quad core, the new one is an Intel I-7 six core. Both hardwired to the Belkin N router. My old XP PCs do not have this problem.