mssqlserver 2014 backup to disk crashing host on windows 2012R2

Setting up updated mssqlserver host ( older dell R710 ) with windows 2012R2 std and SQL server 2012 Std edition with 96 gb Ram.

SQLserver is allocated 64 GB ram.

Our user database sizes are 650 Gb and 1.5 Tb .  Data devices reside  in DAS and we use Volume mount points.

While backing up the 650 Gb db to local disk in raid 5   separate from root disk it crashes the windows host.

We are using default compression for sql server 2014.

While setting up the sql server databases I did had to do "EnableLUA" in registry to continue to use local administrator login and  privilege for sqlserver.

Any lead will be helpful.

Thanks in advance.

M Paul