Dell XPS 8700 and MS Server 2012r2

Just trying to repurpose an XPS 8700 we acquired and use it as a software testing server.  We'd like to install Server 2012r2 on it but have hit a snag.

The disk requests and performs repartitioning without issue, accepts the license code, but pauses and eventually fails at 91% of "Getting files ready for installation".  At 91% it will sit doing nothing until you try to intervene (open disk drive for example), at which point it says it cannot install required files and throws a 0x80070015 error.

I've tried using the internal dvd drive, an external USB dvd drive, and 3 different disks.  Any thoughts how I can get past this, if I even can?  I understand Dell doesn't support higher than W10 on this box...but hoping that only means they won't support it, not that it can't be done.