setting up graphics card driver for KDE , like in NRR or Manjaro just as well, can be quite an ordeal.
Especially when switching over to a different card or booting your NRR installation on a different machine.
[*]grub timeout 5 seconds is too short. you don’t see anything. use 15 seconds instead.
[*]setting up BIOS correctly must be done beforehand. With the target card, it may be impossible to see anything in BIOS setup. You can still navigate blindly in BIOS, of course.
[*]nividia340 and nvidia304 packages exclude each other, but after telinit 3 you can un/Install the packages. Or use a different, less troublesome, gfx card.
[*]try out stuff with the live-CD to see whether it works at all. may be necessary to edit the kernel params in boot menu (ati and nvidia “no modeset” stuff).
[*]amazingly, even older cards can be made to function after a lot of meddling.
[*]use the fallback bootentry which loads all drivers. You can still end up boot-looping and kernel-dumping though, even with kern416 and 2018.1 NRR.