After installing the drivers I do see the device in the OS! Unfortunately, I do not believe using an Nvidia GPU like the Quadro P400 is possible with standard Nvidia drivers. I am getting error code 43 as I now read so many others are...

I removed my pci device from the vm using the following command:

xe vm-param-remove param-name=other-config uuid=6ffb8f66-297e-98ef-f7c9-2c930c5e4ce2 param-key=pci 0/0000:01:00.0,1/0000:01:00.1

To see parameters of the vm in general I used:

xe vm-param-list uuid=6ffb8f66-297e-98ef-f7c9-2c930c5e4ce2

I tested in Debian 10 and have similar problems when trying to use the card. The card is visible but will not run.

root@debian:/home/user# nvidia-detect
Detected NVIDIA GPUs:
00:05.0 VGA compatible controller [0300]: NVIDIA Corporation GP107GL [Quadro P400][10de:1cb3] (rev a1)

Checking card:  NVIDIA Corporation GP107GL [Quadro P400] (rev a1)
Your card is supported by the default drivers and legacy driver series 390.
It is recommended to install the
    nvidia-driver

root@debian:/home/user# apt install nvidia-driver 
root@debian:/home/user# apt install nvidia-smi

root@debian:/home/user# nvidia-smi
Unable to determine the device handle for GPU 0000:00:05.0: Unknown Error

@olivierlambert
I just ran these commands and I still can use the console window and do not see it in device manager.

[10:39 xcp-ng2 ~]# lspci
00:00.0 Host bridge: Intel Corporation Xeon E3-1200 v2/Ivy Bridge DRAM Controller (rev 09)
00:01.0 PCI bridge: Intel Corporation Xeon E3-1200 v2/3rd Gen Core processor PCI Express Root Port (rev 09)
00:1a.0 USB controller: Intel Corporation 6 Series/C200 Series Chipset Family USB Enhanced Host Controller #2 (rev 04)
00:1c.0 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 1 (rev b4)
00:1d.0 USB controller: Intel Corporation 6 Series/C200 Series Chipset Family USB Enhanced Host Controller #1 (rev 04)
00:1e.0 PCI bridge: Intel Corporation 82801 PCI Bridge (rev a4)
00:1f.0 ISA bridge: Intel Corporation C202 Chipset LPC Controller (rev 04)
00:1f.2 SATA controller: Intel Corporation 6 Series/C200 Series Chipset Family 6 port Desktop SATA AHCI Controller (rev 04)
00:1f.3 SMBus: Intel Corporation 6 Series/C200 Series Chipset Family SMBus Controller (rev 04)
01:00.0 VGA compatible controller: NVIDIA Corporation GP107GL [Quadro P400] (rev a1)
01:00.1 Audio device: NVIDIA Corporation GP107GL High Definition Audio Controller (rev a1)
02:00.0 Ethernet controller: Broadcom Inc. and subsidiaries NetXtreme II BCM5716 Gigabit Ethernet (rev 20)
02:00.1 Ethernet controller: Broadcom Inc. and subsidiaries NetXtreme II BCM5716 Gigabit Ethernet (rev 20)

[10:40 xcp-ng2 ~]# xl pci-assignable-list
0000:01:00.0
0000:01:00.1
[10:41 xcp-ng2 ~]# xe vm-param-set other-config:pci=0/0000:01:00.0,1/0000:01:00.1 uuid=6ffb8f66-297e-98ef-f7c9-2c930c5e4ce2
[10:42 xcp-ng2 ~]#

@olivierlambert Man I am on a roll with dumb questions in this forum... Only now do I see that dialog says vGPU.

Hello,

I've been successful in presenting XCP-NG and XO a GPU... But I cannot get it to pass through. I feel like I am missing something.

Dell R210 II Xeon E3-1230 V2
Nvidia P400 (UEFI removed/vBIOS hack)
Windows 10 Pro Oct 2020 with XCP-NG guest tools 8.2.2.200-rc1

passthrough () 0x0 is shown... Not sure if that is right, but when booting the machine isn't detecting it.

The GPU passthrough section doesn't say much on the docs https://xcp-ng.org/docs/compute.html#gpu-passthrough

Any help would be appreciated.

I am trying to move XO to a new host and I am not seeing interfaces or disks available to me when creating VMs. This is strange to me as both of these are showing under host and XO is obviously using them to run... I suspect they need some reconfiguration.

Your help is greatly appreciated.