How are you doing the backup and restore? The best way is to delete the RAID 5, create the RAID 10, reinstall windows from system management tools and documentation disk, which will create the new EFI and dellutility partitions and then restore. However if you are not wanting to do this, the system should work without the utility partition, but if it is a GPT partition and in UEFI mode the EFI partition is needed and the data in it, so that has to be restored as well, a blank one probably will not allow the system to boot properly.
Hello, I have two Power Edge T620's, with  PERC H710 Adapters. The servers are configured with 10 300GB 10K SAS disks, in RAID 5. I have inherited this setup from a previous sysadmin, and would like to change it to a RAID 10 setup. I am running Hyper-v 2012 server core with 2 VM's on them, both  Win2k8 r2, one as SQL server, the other as terminal server. The SQL server has performance issues which are connected to Disk I/O, and im hoping that the RAID 10 setup will improve the I/O performance.  The T620's are identical, one is a production server, the other is for testing/hardware failover. My question is, can i restore the EFI System and DELLUTILITY partitions after i change the raid setup, or just create a new EFI system partition, and then work without the DELLUTILTY partition?
DELL PE 620T - change RAID Setup