After trying multiple times to" upgrade " to win 10 and failed, i finally created a bootable iso, used rufus to burn it to a pendrive and clean installed the os onto my ssd.. while booting from the pendrive i had to the change the boot mode from uefi to legacy .. now the after installation i tried to change the boot mode back to uefi . but if the ssd is not available as a boot device in uefi .. its available only in legacy . the system is working fine though. is ther any reason i would need to change the boot mode to uefi ? just curious..