How to use dual graphics cards and multiple monitors on Ubuntu 18.04 with Nvidia GeForce GTX 1050

Question

I have got Mac Pro Server 2008 and I have installed additional GTX 1050 GPU for Deep Learning .. etc. Now I want to use both Graphic Cards at the same time. I have got 2 monitors (LCD Displays) connected to the old graphics card (GeForce 8800 GT).

If I run the following command, I get:

    $ lspci -k | grep -EA3 'VGA|Display'
02:00.0 VGA compatible controller: NVIDIA Corporation GP107 [GeForce GTX 1050 Ti] (rev a1)
    Subsystem: NVIDIA Corporation GP107 [GeForce GTX 1050 Ti]
    Kernel driver in use: nvidia
    Kernel modules: nvidiafb, nouveau, nvidia_drm, nvidia
--
06:00.0 VGA compatible controller: NVIDIA Corporation G92 [GeForce 8800 GT] (rev a2)
    Subsystem: NVIDIA Corporation G92 [GeForce 8800 GT]
    Kernel modules: nvidiafb, nouveau, nvidia_drm, nvidia
07:00.0 Ethernet controller: Intel Corporation 80003ES2LAN Gigabit Ethernet Controller (Copper) (rev 01)

I have checked similar questions and they seem to address the problem for older versions.

In my case I have also got Cuda 10.0 and CudNN 7.3 both installed and running perfectly. I don't want to mess with that. I have also got Nvidia drivers 390 installed and changing that will mess things up as well.

In addition to that when I run the following, I get nothing:

    $ xrandr --listproviders
Providers: number : 0

Another issue is that GeForce 8800 GT detects only one display / monitor and not the second one. I doubt this has something to do with drivers installed.

Please advise how I can connect two monitors to GeForce 8800 GT and keep the GTX 1050 Idle for Deep Learning tasks only.

Thank you.