When Server Core originally shipped, a lot of Windows admins avoided it because you could only use the command line, but this changes with Windows Server 2012 which enabled the use of a hybrid mode.
Turning the GUI Off
In Windows Server 8 the GUI has kept with the modular nature of recent Windows Server Operating Systems and in turn has become a “Feature”. This makes removing the GUI very easy. To get started launch Server Manager.
Click on Manage, and then select Remove Roles or Features from the menu.
Click next to skip past the before you begin page, then select your server from the server pool and click next.
Since the GUI is not a Role, we can just click next again to skip past the Roles section.
When you reach the Features page, you need to uncheck the box next to the “User Interfaces and Infrastructure” option, and then click next.
Now tick the “Restart Destination Server” box, then click remove.
The GUI will now be removed.
After the binaries are removed your server will automatically reboot.
Once it comes back up, and you log in, you will only be able to use the command line.
Turning the GUI On
Once the GUI has been turned off, you will want to know how to get it back. To do this we use SConfig, so go ahead and type SConfig into the command line and hit enter.
You can see near the bottom of the screen that we can use “12” to Restore the GUI, so type 12 and hit enter.
You will be warned that enabling the GUI requires a reboot, click the yes button.
That will kick off DISM which will start to add the binaries for the GUI Shell.
When its finished you will be asked if you would like to restart the computer now, type “y” and hit enter to reboot.
GUI Off with PowerShell
You can do the same thing as we did in the GUI much quicker with a PowerShell cmdlet. To do so, open Server Manager, click on Tools and launch PowerShell.
We can use the Remove-WindowsFeature cmdlet to remove the feature:
Remove-WindowsFeature Server-Gui-Shell, Server-Gui-Mgmt-Infra
Since Remove-WindowsFeature is just an alias, you could also use:
Uninstall-WindowsFeature Server-Gui-Shell, Server-Gui-Mgmt-Infra
Not long after you have hit the enter key, the removal will begin.
When it’s done, you will be notified that you need to restart your server to complete the process, which can be easily done from the current PowerShell window by running:
Shutdown –r -t 0
When your machine restarts you will only have the command line to work with .
GUI On with PowerShell
The first thing we need to do is get into PowerShell, so type PowerShell and hit enter.
Now we need to use the Add-WindowsFeature to add the components back:
Add-WindowsFeature Server-Gui-Shell, Server-Gui-Mgmt-Infra
Again this is just an alias for:
Install-WindowsFeature Server-Gui-Shell, Server-Gui-Mgmt-Infra
When its done, we will need to restart our server by using the Shutdown command:
Shutdown –r -t 0
When your server reboots you will have the GUI back.
출처 : http://www.howtogeek.com/111967/how-to-turn-the-gui-off-and-on-in-windows-server-2012/