Maybe this is much simpler than i think: i am testing a SCCM deployment on a HP Compaq machine. I had problems with some drivers, so i had to repeat the installation multiple times in one day. After every deployment, there is a new entry named "Windows Boot Manager" in the Boot Device Selection. I am not able to remove them - is there a way to clean this without resetting Bios to default values?
What i tried so far is cleaning the disk with Diskpart, which did not change anything.
Do you have UEFI enabled? If so, you may want to disable UEFI. If you are PXE booting into the Legacy BIOS, you are formatting the drive using the Legacy format. So when you reboot, if UEFI is enabled, you should be receiving "Windows Boot Manager".
http://www.tenforums.com/installation-setup/32127-uefi-windows-boot-manager.html https://www.happyassassin.net/2014/01/25/uefi-boot-how-does-that-actually-work-then/