Afaik, you should at least be able to boot into the system, maybe you can try to but into a arch boot image and read the log files.
If you have some more information you could check this guide:
Foxtrot Mike via arch-general firstname.lastname@example.org schrieb am Sa., 30. Dez. 2017, 18:54:
I was using amd r7 260x card without any problem with 'amdgpu' module. Now I want to install my new nvidia card (1050ti). I assumed that installing 'nvidia' package from pacman would be enough to be able to use my new GPU. (Apparently not).
The nvidia related packages installed on my PC are:
~$ pacman -Qs nvidia local/libvdpau 1.1.1+3+ga21bf7a-1 Nvidia VDPAU library local/nvidia 387.34-15 NVIDIA drivers for linux local/nvidia-utils 387.34-2 NVIDIA drivers utilities
Upon rebooting after switching the cards, arch boots fine until "Reached target graphical interface" appears on the display. It seemed the PC was stuck, but switching to tty2 resulted in flashing keyboard lights. Which, according to a quick Google search, means kernel panic.
Moreover,  says that "the files are read in ASCII order, and by convention their names start with XX- (two digits and a hyphen, so that for example 10 is read before 20).". But I have multiple files in "/usr/share/X11/xorg.conf.d" starting with the same number 10:
~$ ls /usr/share/X11/xorg.conf.d/ 10-amdgpu.conf 10-quirks.conf 10-nvidia-drm-outputclass.conf 40-libinput.conf
Please help me in getting my new card up and running.