- New update now with stretch+backports kernel+firmware-nonfree it's a bit better.
- If you want to know DP works like vga (I had a dp cable around so I tested it)
- I also blacklisted sp5100_tco to get rid of that nasty already in use error (I think doesn't create any problem to the system, despite I would have preferred some more clean solution to it)
- Also the ACPI bios bug disappeared after blacklisting sp5100_tco (I don't know why or if it's related seems odd)
Now my dmesg error level is considerably lower:
[ 2.253391] BERT: Can't request iomem region <00000000dd91c018-00000000dd91c02b>.
[ 5.215462] kfd kfd: error getting iommu info. is the iommu enabled?
[ 5.215527] kfd kfd: Error initializing iommuv2 for device (1002:9874)
[ 5.215758] kfd kfd: device (1002:9874) NOT added due to errors
I found this article about kfd error https://community.amd.com/thread/170292 but the fix didn't worked out for me unfortunately.
At the beginning I had also a warning about usb power management, but after a couple of reboot just disappeared 
it remains just the annoying kfd iommu info, why does it try to load it if it's disabled on the bios is beyond me, I will try to look at the fix you mentioned of iommu
but at least I think it's just cosmetic, so we are good!
Indeed you were really helpful @qwertz123 thanks a lot!
It is a good looking machine for the price point and consumption, I've another around, I'm considering to use it in a small office with 5\6 users to use samba\share where they work coupled with 2 data disks+ 2
disk with rsnapshot to have backup of the data disks (I'm not really a raid guy, I prefere snasphots so you can go back in time) plus teamviewer host to let them turn on their pc and work from home if needed.
I hope the amd apu can handle it, it shouldn't be too much difficult for it, indeed 5 users are not too much, so I hope will handle everything.
Interesting choice with your upgrades plan, especially about the ram upgrade are you planning use zfs or just to have as much power as you could?
I love the components for the price, especially the ecc support, leaving open road to future zfs upgrade aswell.
Quote from qwertz123
I used the minimal/network iso and the graphical expert install, since I wanted only the minimal system. Afterwards just added the OMV repository to sources.list and installed the packages according to the wiki.
I did the same but I could only find one for kralizec in the official wiki
Anyway I think not much is changed so I went ahead and went with:
echo "deb http://packages.openmediavault.org/public arrakis main" > /etc/apt/sources.list.d/openmediavault.list
apt-get install --allow-unauthenticated openmediavault-keyring
apt update
apt install postfix
apt install openmediavault
omv-initsystem
It looks that everything is ok, but I don't know if I need other packages for arrakis, I hope not.