@andyhhp Sorry again for slow replies, thanks for the help here!
This is the output of lspci -tv:
[13:23 xcp-ng ~]# lspci -tv
-+-[0000:40]-+-00.0 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-0fh) Root Complex
| +-00.2 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-0fh) I/O Memory Management Unit
| +-01.0 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-1fh) PCIe Dummy Host Bridge
| +-02.0 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-1fh) PCIe Dummy Host Bridge
| +-03.0 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-1fh) PCIe Dummy Host Bridge
| +-03.1-[41]--+-00.0 NVIDIA Corporation GM206 [GeForce GTX 960]
| | \-00.1 NVIDIA Corporation GM206 High Definition Audio Controller
| +-04.0 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-1fh) PCIe Dummy Host Bridge
| +-07.0 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-1fh) PCIe Dummy Host Bridge
| +-07.1-[42]--+-00.0 Advanced Micro Devices, Inc. [AMD] Zeppelin/Raven/Raven2 PCIe Dummy Function
| | +-00.2 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-0fh) Platform Security Processor
| | \-00.3 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-0fh) USB 3.0 Host Controller
| +-08.0 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-1fh) PCIe Dummy Host Bridge
| \-08.1-[43]--+-00.0 Advanced Micro Devices, Inc. [AMD] Zeppelin/Renoir PCIe Dummy Function
| \-00.2 Advanced Micro Devices, Inc. [AMD] FCH SATA Controller [AHCI mode]
\-[0000:00]-+-00.0 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-0fh) Root Complex
+-00.2 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-0fh) I/O Memory Management Unit
+-01.0 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-1fh) PCIe Dummy Host Bridge
+-01.1-[01-07]--+-00.0 Advanced Micro Devices, Inc. [AMD] X399 Series Chipset USB 3.1 xHCI Controller
| +-00.1 Advanced Micro Devices, Inc. [AMD] X399 Series Chipset SATA Controller
| \-00.2-[02-07]--+-00.0-[03]----00.0 Aquantia Corp. AQC107 NBase-T/IEEE 802.3bz Ethernet Controller [AQtion]
| +-04.0-[04]----00.0 Intel Corporation I211 Gigabit Network Connection
| +-05.0-[05]----00.0 Intel Corporation Dual Band Wireless-AC 3168NGW [Stone Peak]
| +-06.0-[06]----00.0 Intel Corporation I211 Gigabit Network Connection
| \-07.0-[07]--
+-02.0 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-1fh) PCIe Dummy Host Bridge
+-03.0 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-1fh) PCIe Dummy Host Bridge
+-03.1-[08]--+-00.0 Advanced Micro Devices, Inc. [AMD/ATI] Ellesmere [Radeon RX 470/480/570/570X/580/580X/590]
| \-00.1 Advanced Micro Devices, Inc. [AMD/ATI] Ellesmere HDMI Audio [Radeon RX 470/480 / 570/580/590]
+-04.0 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-1fh) PCIe Dummy Host Bridge
+-07.0 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-1fh) PCIe Dummy Host Bridge
+-07.1-[09]--+-00.0 Advanced Micro Devices, Inc. [AMD] Zeppelin/Raven/Raven2 PCIe Dummy Function
| +-00.2 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-0fh) Platform Security Processor
| \-00.3 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-0fh) USB 3.0 Host Controller
+-08.0 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-1fh) PCIe Dummy Host Bridge
+-08.1-[0a]--+-00.0 Advanced Micro Devices, Inc. [AMD] Zeppelin/Renoir PCIe Dummy Function
| +-00.2 Advanced Micro Devices, Inc. [AMD] FCH SATA Controller [AHCI mode]
| \-00.3 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-0fh) HD Audio Controller
+-14.0 Advanced Micro Devices, Inc. [AMD] FCH SMBus Controller
+-14.3 Advanced Micro Devices, Inc. [AMD] FCH LPC Bridge
+-18.0 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-0fh) Data Fabric: Device 18h; Function 0
+-18.1 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-0fh) Data Fabric: Device 18h; Function 1
+-18.2 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-0fh) Data Fabric: Device 18h; Function 2
+-18.3 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-0fh) Data Fabric: Device 18h; Function 3
+-18.4 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-0fh) Data Fabric: Device 18h; Function 4
+-18.5 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-0fh) Data Fabric: Device 18h; Function 5
+-18.6 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-0fh) Data Fabric: Device 18h; Function 6
+-18.7 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-0fh) Data Fabric: Device 18h; Function 7
+-19.0 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-0fh) Data Fabric: Device 18h; Function 0
+-19.1 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-0fh) Data Fabric: Device 18h; Function 1
+-19.2 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-0fh) Data Fabric: Device 18h; Function 2
+-19.3 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-0fh) Data Fabric: Device 18h; Function 3
+-19.4 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-0fh) Data Fabric: Device 18h; Function 4
+-19.5 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-0fh) Data Fabric: Device 18h; Function 5
+-19.6 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-0fh) Data Fabric: Device 18h; Function 6
\-19.7 Advanced Micro Devices, Inc. [AMD] Family 17h (Models 00h-0fh) Data Fabric: Device 18h; Function 7
I would also note that this system was known 100% functional before being setup with XCP-ng, so it's possible it's something that needs reseating but I think an actual hardware failure issue is unlikely. Not impossible since I did transplant it to a new case (was originally my desktop) but I'm quite careful and very experienced with that sort of thing.
This upcoming weekend, assuming I have time, maybe I will give it a real good cleaning and reseat everything, then attempt GPU passthrough again.