GPU Passthrough (unable to read tail (got 0 bytes))

[arnoproxmox]

Hi to all,

When my PC build was finished I installed Proxmox.
My goal is to start two VM's at the same time. On one VM I want to use passthrough of a GPU.

All is OK until...
I add a PCI device for the GPU.
Then I get the following:

Error: unable to read tail (got 0 bytes)

When I delete the PCI device the VM starts.
I don't know what you want to know but let's start with

Chipset: Z390
BIOS: vt-d enabled
CPU: i9900KF
GPU: 2x Nvidia GeForce GT 710B (one for proxmox, one for VM)

Can this be done with GPU's of the same type?

pveversion -v
proxmox-ve: 6.3-1 (running kernel: 5.4.103-1-pve)
pve-manager: 6.3-6 (running version: 6.3-6/2184247e)
pve-kernel-5.4: 6.3-7
pve-kernel-helper: 6.3-7
pve-kernel-5.4.103-1-pve: 5.4.103-1
pve-kernel-5.4.73-1-pve: 5.4.73-1
ceph-fuse: 12.2.11+dfsg1-2.1+b1
corosync: 3.1.0-pve1
criu: 3.11-3
glusterfs-client: 5.5-3
ifupdown: 0.8.35+pve1
ksm-control-daemon: 1.3-1
libjs-extjs: 6.0.1-10
libknet1: 1.20-pve1
libproxmox-acme-perl: 1.0.7
libproxmox-backup-qemu0: 1.0.3-1
libpve-access-control: 6.1-3
libpve-apiclient-perl: 3.1-3
libpve-common-perl: 6.3-5
libpve-guest-common-perl: 3.1-5
libpve-http-server-perl: 3.1-1
libpve-storage-perl: 6.3-7
libqb0: 1.0.5-1
libspice-server1: 0.14.2-4~pve6+1
lvm2: 2.03.02-pve4
lxc-pve: 4.0.6-2
lxcfs: 4.0.6-pve1
novnc-pve: 1.1.0-1
proxmox-backup-client: 1.0.11-1
proxmox-mini-journalreader: 1.1-1
proxmox-widget-toolkit: 2.4-6
pve-cluster: 6.2-1
pve-container: 3.3-4
pve-docs: 6.3-1
pve-edk2-firmware: 2.20200531-1
pve-firewall: 4.1-3
pve-firmware: 3.2-2
pve-ha-manager: 3.1-1
pve-i18n: 2.2-2
pve-qemu-kvm: 5.2.0-3
pve-xtermjs: 4.7.0-3
qemu-server: 6.3-8
smartmontools: 7.2-pve2
spiceterm: 3.1-1
vncterm: 1.6-2
zfsutils-linux: 2.0.3-pve2
root@GATIEN:~# pveversion
pve-manager/6.3-6/2184247e (running kernel: 5.4.103-1-pve)
root@GATIEN:~# pveversion -v
proxmox-ve: 6.3-1 (running kernel: 5.4.103-1-pve)
pve-manager: 6.3-6 (running version: 6.3-6/2184247e)
pve-kernel-5.4: 6.3-7
pve-kernel-helper: 6.3-7
pve-kernel-5.4.103-1-pve: 5.4.103-1
pve-kernel-5.4.73-1-pve: 5.4.73-1
ceph-fuse: 12.2.11+dfsg1-2.1+b1
corosync: 3.1.0-pve1
criu: 3.11-3
glusterfs-client: 5.5-3
ifupdown: 0.8.35+pve1
ksm-control-daemon: 1.3-1
libjs-extjs: 6.0.1-10
libknet1: 1.20-pve1
libproxmox-acme-perl: 1.0.7
libproxmox-backup-qemu0: 1.0.3-1
libpve-access-control: 6.1-3
libpve-apiclient-perl: 3.1-3
libpve-common-perl: 6.3-5
libpve-guest-common-perl: 3.1-5
libpve-http-server-perl: 3.1-1
libpve-storage-perl: 6.3-7
libqb0: 1.0.5-1
libspice-server1: 0.14.2-4~pve6+1
lvm2: 2.03.02-pve4
lxc-pve: 4.0.6-2
lxcfs: 4.0.6-pve1
novnc-pve: 1.1.0-1
proxmox-backup-client: 1.0.11-1
proxmox-mini-journalreader: 1.1-1
proxmox-widget-toolkit: 2.4-6
pve-cluster: 6.2-1
pve-container: 3.3-4
pve-docs: 6.3-1
pve-edk2-firmware: 2.20200531-1
pve-firewall: 4.1-3
pve-firmware: 3.2-2
pve-ha-manager: 3.1-1
pve-i18n: 2.2-2
pve-qemu-kvm: 5.2.0-3
pve-xtermjs: 4.7.0-3
qemu-server: 6.3-8
smartmontools: 7.2-pve2
spiceterm: 3.1-1
vncterm: 1.6-2
zfsutils-linux: 2.0.3-pve2

This is what I did to install (CE version):

apt full-upgrade
Extra's:
ssh server
desktop environment: Cinnamon

GRUB_CMDLINE_LINUX_DEFAULT="quiet intel_iommu=on"
update-grub

/etc/modules
vfio
vfio_iommu_type1
vfio_pci
vfio_virqfd

VM:
100.conf
agent: 1
bios: ovmf
boot: order=ide2;scsi0;net0
cores: 4
cpu: host
efidisk0: local-lvm:vm-100-disk-1,size=4M
ide0: local:iso/virtio-win-0.1.190.iso,media=cdrom,size=489986K
ide2: local:iso/windows10.iso,media=cdrom
machine: q35
memory: 8192
name: TestGPU
net0: virtio=9A:C32:40:7E:3F,bridge=vmbr0,firewall=1
numa: 0
ostype: l26
scsi0: local-lvm:vm-100-disk-0,size=50G,ssd=1
scsihw: virtio-scsi-pci
smbios1: uuid=9c2803d9-ac58-48fc-9689-5a8bb183c6ee
sockets: 1
vga: std
vmgenid: e8fffd12-c7f4-4be1-bd8f-cc744b7900e2

Thanks for your help,
Arno