I think I have come to terms with the fact that Dell servers ship with exceptionally poor onboard devices.

The cheaper broadcom ethernet controller have had a less than stellar track record, across both BSD and Linux systems here.

Before I Google it yet again, this is the boot option required to install Fedora 20 onto a Dell server with a broadcom controller:

 modprobe.blacklist=cnic,bnx2i

This will not load a kernel module during install, which crashes the Anaconda installer.

Poor Steve just spent all morning fighting it…