CentOS and the Asus M3A78-CM Gigabit Ethernet Controller
If you’re installing CentOS 5.2 or similar on an Asus M3A78-CM motherboard, make sure you grab the M3A76 Linux driver package Asus provides here in the section labeled “Others”.
On a clean install, CentOS loads a Realtek driver which appears to work. The eth0 interface shows up, but if you’re using DHCP it fails to get an address. The physical port and your swich will show a link, but the network doesn’t work. The driver CentOS loads for this board’s integrated ethernet doesn’t work.
To fix the problem, install the Linux driver provided by the manufacturer:
Download this and extract the LAN driver to a directory, then:
# make clean modules
# make install
# depmod -a
# insmod ./src/r8168.ko (or r8168.o in linux kernel 2.4.x)
and reboot!