The Oracle Linux UEK 7.1 GUI might not start in Legacy BIOS Boot Mode.
Workaround
Install the x11/mga driver.
rpm -ivh xorg-x11-drv-mga-1.6.3-5.el6.x86_64.rpm
Create a entry in the file /etc/X11/xorg.conf.d
Section "Device" Identifier "Videocard0" Driver "mga" EndSection
Reboot your server.