Okay, as I said, I cannot help much with graphic and suggest you search the forum.
If you have no further assistance from someone else or you cannot find a satisfactory answer.
My suggestion is that at prompt,
Remove all what’s listed in ‘mhwd -li’ by
sudo mhwd -r <what's installed in mhwd -li>
sudo mhwd -a pci free 0300
If someone else comes along, or you find a better search, follow that.
ps: It confirms it’s a graphic issue and not an installation problem.
 - with new installation, always do first this when you reached prompt
sudo pacman-mirrors -g
sudo pacman -Syyu