On Sun, 9 Mar 2014, P J wrote:
James & Paul,
Thank you for your suggestions, I will give them a try.
Paul, it is indeed a SuperMicro with onboard Intel 82574L's. So I will try the kmod-e1000e package as well.
Don't neglect the pcie_aspm=off in grub.conf; that and the elrepo package made the problem go away for me.