The system will boot from the partition only if it has Active flag set.
diskpart
list disk
Remember the desired disk number
select disk #
where # is the desired disk number
list partition
Remember the desired partition number
select partition #
where # is the desired partition number
active
diskpart
list disk
Remember the desired disk number
select disk #
where # is the desired disk number
list partition
Remember the desired partition number
select partition #
where # is the desired partition number
inactive
Backup & Recovery, Drive Copy, Hard Disk Manager™ for Windows, HowTos, HowTos: Windows, Migrate OS to SSD, Recovery Media, Rescue Kit, RMB: WinPE
Tags: active, boot, disk, partition, windows