Want use 2 gpus on my system (nvidia+radeon rx vega 56)

Hi!

On my system, first gpu is a Nvidia card.

I bought a second graphics card called "Radeon RX Vega 56".

I plugged in the "Radeon RX Vega 56" into my system and boot up my PC.

Logged into my Desktop, Nvida driver works.

AMDgpu modules are loaded, "Radeon RX Vega 56" is in my system as a second graphics card.

Since I have the plugged in th "Radeon RX Vega 56" into my
system, my desktop works extremely slowly.

I removed the "Radeon RX Vega 56" again, rebooted my PC and my desktop is working fast again.

I use Compiz.
Also blacklisted "amdgpu+radeon" under Compiz.

However, this did not bring success.

I want to use the second graphics card with Qemu (Virtualization) and should not be used in my main system.

I blacklisted amdgpu module before. No success.

Any ideas where he could be?

Kernel: 5. 0. 0-38-generic (on Ubuntu Mate 19. 04)

I disabled my Onboard-Soundcard because I have trouble with that and removed
PulseAudio.

So, got it now, but the fan of my 2nd card is very loud.

Working on my Desktop is fast, again.

# lspci | grep -i vga

01:00.0 VGA compatible controller: NVIDIA Corporation GP106 [GeForce GTX 1060 6GB] (rev a1)
04:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Vega 10 XT [Radeon RX Vega 64] (rev c3)