you dont need that line ,
see this
https://wiki.manjaro.org/index.php?title=Configure_Graphics_Cards
in terminal or TTY
for free drivers
sudo mhwd -a pci free 0300
for no free drivers
sudo mhwd -a pci nonfree 0300
then reboot
you dont need that line ,
see this
https://wiki.manjaro.org/index.php?title=Configure_Graphics_Cards
in terminal or TTY
for free drivers
sudo mhwd -a pci free 0300
for no free drivers
sudo mhwd -a pci nonfree 0300
then reboot