As I understand your question, do you want to install switchdesk
$ yum install switchdesk switchdesk-gui
and run it. You can also try changing the settings in /etc/sysconfig/desktop , as described here .
If you just want to try a different desktop environment while logging in, try installing lightdm or kdm (from the great people who bring KDE to us) and choose one before you log in.
EDIT Tip may be out of date.
GDM does not seem to allow you to choose your desktop environment like KDM and lightdm (and others) do. Using my favorite DM, lightdm, as an example (use sudo or switch to root):
$ sudo yum install lightdm ... $ sudo systemctl reboot
This can be done without rebooting.
$ sudo systemctl stop gdm
Log in as root and then type
$ systemctl start lightdm
When I change DM, I like to reboot so that my changes are saved. If (like mine) your machine does not boot to the graphic screen, log in as root and enter:
$ systemctl start lightdm
Both KDM and lightdm allow you to select DE from the drop-down menu.
If you want to return to the Gnome display manager:
$ sudo systemctl enable gdm $ sudo systemctl disable lightdm