Hybrid GPU setup (AMD/NVIDIA)

Used cards were a MSI RX570 and a Gigabyte 1650 Super

Prerequisites

Initially I had removed all drivers, and then installed drivers for the mounted RX570 by

sudo mhwd -a pci free 0300

To make this card work on its own I had to rename the following files:

/etc/X11/xorg.conf -> /etc/X11/xorg.conf.bak
/etc/xorg.conf.d/90-mhwd.conf -> /etc/xorg.conf.d/90-mhwd.conf.bak

/usr/share/X11/xorg.conf.d/20-nvidia.conf -> /usr/share/X11/xorg.conf.d/20-nvidia.conf.bak

/usr/share/X11/xorg.conf.d/10-amdgpu.conf -> /usr/share/X11/xorg.conf.d/20-amdgpu.conf

The AMD card was now mounted and working properly with the video-linux driver.

Dual GPU configuration

I mounted the NVIDIA gpu and both cards were recognized. Installing the video-hybrid-amd-nvidia-prime driver via the mhwd made both cards work flawlessly, at least for my purposes.

CUDA & OpenCL

In order to have CUDA and OpenCL working properly for both cards, appropriate packages must be installed.

CUDA was simply installed by

sudo pacman -Syu cuda

While OpenCL for the AMD card was achieved from the AUR package opencl-amd