hp elitedesk 400 g3 enable legacy boot

[YUBA]

Hi All,
i have HP elitedesk 400 g3 and when ever i enable the legacy boot on the bios settings , it returns back to be disabled i have tried every thing disable what ever security is there, and then i save and reboot on the change 4 digit code and then i find it returned back to be disabled.
Note: The computer is new and has no operating system

[WAWood]

@YUBA 

Why don't you start by telling us WHAT you are hoping to accomplish by doing this?

A new Elitedesk would come with Win10 preloaded, not "no OS" as you indicated.

So, are you trying to get into legacy mode to install a Linux distro?

IF so, since we aren't equipped here to provide detailed Linux support, your best bet then would be to contact the support forum for the Linux distro you are planning to install.