To restore a single CPU from a USB backup, follow the procedure provided in the DSC 8000 Servicing Field Replaceable Units (FRUs), starting at the section titled, To boot up the BIOS.
You can use the DSC Web UI to back up the system (OS and data) to a USB key, however, restoring a complete system (cold install) from a USB key is not a supported action for end-users. If you have experienced a catastrophic system failure that requires this action, contact Customer Support.