then try this
TTY
sudo pacman -Syyu
sudo mhwd -a pci free 0300
sudo mhwd -a pci nonfree 0300
or under chroot ( with USB live Iso )
sudo manjaro-chroot -a
pacman -Syyu
mhwd -a pci free 0300
mhwd -a pci nonfree 0300
exit ( end-chroot )
check also version xorg config from nvidia-setting
see this