As mentioned above, the nouveau driver should work. Use that if you don’t need the additional features of the Nvidia driver.
Try nvidia-inst:
sudo pacman -Syu nvidia-inst # install the package
nvidia-inst -h # get some help
nvidia-inst -t # test it without changing anything
and show the results here.
If everything seems OK, then run
# This step is needed for 470 and 390 series drivers, adds a new package source to /etc/pacman.conf
nvidia-inst --legacyrepo
# Install Nvidia legacy drivers
nvidia-inst