Z420 Workstation - "928-Fatal PCIe error... ...Completion timeout" GPU passthrough with r9 380, kvm

[Stryder01]

I am currently using an HP z420 workstation, with a xeon e5 2660 CPU, and gentoo linux installed. I have the latest BIOS and firmware. I have two video cards installed: the NVIDIA GeForce GT 310 that came with the system and an AMD R9 280 2GB. I am trying to use a qemu/kvm virtual machine and passthrough the r9 380 to a windows 10 guest. When I started the virtual machine at first, it worked with functioning output. I proceeded to install the drivers for the card in the virtual machine. Then, the whole system instantly reset and presented the following error during bootup:

928-Fatal PCIe error. 
    PCIe error detected Slot 2
    Completion timeout

I dont think I can even start that vm anymore without this happening, and I also attempted passing through the video card to a linux guest and the same error occured, before i even installed any drivers.

The r9 380 appears to function fine in a host machine. The error also occurs with an rx 560.

Is this a problem with the motherboard? Is there a potential solution to this?

[ready2assist]

Hi yes it is the issue with the system board and the only fix is to replace the system board. Please contact Hp Technical support to check and replace the system board.

[RajDebashish]

Thank you for posting on HP Forums,

installs Red Hat Enterprise Linux 6 (x86_64) on an HP Z workstation with two or more NVIDIA graphics cards configured, the system may reboot automatically and have following error during POST.

Resolutions:
To resolve this issue, select " Install system with basic video driver" on the boot menu, or use the nomodeset xdriver=vesa boot option at the boot prompt.

928 - Fatal PCIe Error
PCIe error detected slot 5
Completion Timeout

Debashish
I am an HP Employee
If the information I've provided was helpful,
give us some reinforcement by clicking the solution and kudos buttons,

[Stryder01]

Ok - i guess ill just get a new board - probably a different one i know will work for hardware virtualization. Thank you.