:install the basic set of packages needed to get X started up:
pacman -Sy xorg-server xorg-xinit xorg-xclock xterm twm xf86-video-fbdev
startx
/etc/X11/xorg.conf.d/10-screen.conf
Section
"Screen" Identifier
"Default Screen" Monitor
"Generic Monitor" DefaultDepth 24
SubSection
"Display" Modes "1280x1024"
EndSubSection
EndSection