So hit "Restore Settings" button next to exit, select "Factory Setting" then OK.
Exit will restart your system. Hit F2 to get back in BIOS. Make your settings and don't forget to uncheck "Enable UEFI..." under Security-> UEFI Capsule... sub-menu. Apply and exit.
Undervolt should work in Windows now.
PS: some users on Reddit report that is enough to do the factory reset in BIOS without downgrading on most systems. Seems that idiot Dell engineers forgot to set the lock for the bios factory load config.
Exit will restart your system. Hit F2 to get back in BIOS. Make your settings and don't forget to uncheck "Enable UEFI..." under Security-> UEFI Capsule... sub-menu. Apply and exit.
Undervolt should work in Windows now.
PS: some users on Reddit report that is enough to do the factory reset in BIOS without downgrading on most systems. Seems that idiot Dell engineers forgot to set the lock for the bios factory load config.