kernel panic on new Dell R815 servers

Issue

• We have lots of Dell R815 servers up and running just fine. Recently we purchased some new ones and can't get RHEL installed on them or even boot from a rescue disk. After much troubleshooting with Dell and swapping parts we determined the new servers have a newer revision of the CPUs. We swapped CPUs between the older servers and the newer to verify the problem does in fact follow the CPU.

The old CPUs dell has listed as

Processor, 6174, 2.2, 12MB, Opteron Magney Core, Decision One 

The newer servers have these CPUs

Processor, 6344, 2.6/2.0, 16MB, OAD, C0

I tried downloading the latest RHEL 6.5 (we were using 6.3) and I can at least boot a rescue disk now but still unable to get a working OS on there. A PXE boot and kickstart will take off and appear to be working but as soon as it reboots it just kernel panics. As stated above if I put the older revision CPUs in from another server it all works. There's some sort of bug for the newer AMD CPUs.