Ethernet Troubles

im not sure if its a hardware or software issue so im not entirely sure where to post this but i have an old Compaq PC that has on board Ethernet. the board is an asus a8n-la, and the Ethernet isnt working properly. i have installed the drivers correctly like normal and still the port doesn't show up on the list even if i have the cable plugged in. this isn't a complete problem because i just installed a pci Ethernet card but i would like to be able to use the on board so i can free up a pci slot. does anyone know the issue?
if the pci card works for ethernet connection then the onboard one is damaged, this happened on my dell and I had to order and install a pci card and disable the onboard ethernet connection.