  No such thing exists. You will need to clean install 2012. You can either order the media from Dell Support, or you can download and use the Evaluation version from Microsoft. You can check your server for the ISO files as well. Server Update Utility can run from Windows or is a repository for SBUU/SMTD for firmware updates. It is not bootable. It also will not help you install the OS. SBUU/SMTD can be used to aid in installing the OS, but you will still need the Essentials media.
I have a (still under warranty) PE T320 purchased with Windows 2012 Essentials preinstalled. I have the COA (certificate of authenticity) but no original install DVD media. Can I download a bootable "factory reset" bootable ISO image to reset the server to the original state and proceed with a Win2012 install onto the new HDD?  I see "Dell Server Update Utility, Windows 64 bit Format, v.16.12.00" on my server's support page, but it appears this requires it be run from the Windows 2012 OS, and is not a bootable ISO... is that correct? Basically I need a bootable SUU.  Then after installing the firmware updates contained in the SUU I would still need media to load the installation files containing the Microsoft ISOs allowing me to exercise downgrade rights to previous Microsoft Windows Server OS versions (as described at [URL]  Or maybe there is a combined SUU/OEM install DVD ISO which does everything to perform a "factory reset" on this system? Can you point me to the URLs to download the correct DVD ISOs?
PE T320 New HDD, Want to Reset to Factory Configuration - But Have No Original 
DVD Media