I am trying to get a Power Edge 2850 and 1850 to run Windows Server 2012, so far It gets past the loading screen then will reboot. I believe it has something to do with the drivers but not sure.
We've been through the process several times here on the forums. Up to 2012 will work, but not 2012 R2; it is not supported and nobody has gotten it to work. I no longer have any 28x0 to test for a workaround ... IF one even exists. Good luck. In the unlikely event you happen to find a solution, be sure to post it.
2012 doesn't run great, but acceptably. 2008 R2 runs great. If you must have 2012 R2, then it is time for a new server.