virtualbox.org

My thought, too. See where it says "Prozessoranzahl". Uncheck that box & reboot. That box is limiting you to one processor.

I don't see that dialog in msconfig (Win 10 1903 Pro 64bit). I assume it must be a server special.

@socratis
I have to explain the situation.
I am not responsible for the Windows machines. I am a Linux specialist having set up the host with VirtualBox and the samba server mentioned above. Both work without problems. The samba VM got its single processor after change and works with its expected performance (very good) presumably because it is running without GUI. Only those dammed Windows VMs raise problems. (You see, I don't like Windows at all. However, I have no choice)
The guy responsible for the Windows-VMs is very poor in English, Thus I have to do all the forum is concerned.
We work remote from different locations.

The checkbox for the Prozessorzahl the Windows specialist only checked to inform me.
The listbox is still greyed out if he unchecks the checkbox.
Also a reboot did change nothing.

@mpack
A already mentioned several times.
Read the thread from the beginning.
2 Windows Server 2016 as guests.

HAKAK wrote:The checkbox for the Prozessorzahl the Windows specialist only checked to inform me.
The listbox is still greyed out if he unchecks the checkbox.
Also a reboot did change nothing.

In my Windows 10 & Server 2016 there is little difference in grays between checked & unchecked. Threw me off for a minute too. I know you said you rebooted. Please show a screenshot of the msconfig box unchecked, then reboot the guest, then show a screenshot of the task manager again. And a screenshot of the device manager with the Processors section opened up:

HAKAK,
I don't really like to quote myself, but did you try this?

socratis wrote:Download a Linux LiveDVD, for example SystemRescueCD. Boot the Win2016 VM from the LiveDVD, accepting the defaults. Once you're at the terminal, enter the following command which will give you the number of CPUs:

• 
  nproc

What's the output?

Will be a little difficult, because I am not sitting in front of the machine concerned.
Maybe tomorrow. will be the task of the Windows guy

Greetings

HAKaK
and real thanks for trying to help

BTW, I just tested the 'msconfig' thingy on my Win10-64 VM. If I have that checkbox enabled, Windows thinks that there's only 1 CPU, even though the VM is configured with two. Unchecking this restores order in the universe...

I think we have the solution.

No problem, Hakak, glad to try.

Interesting, Socratis. Found that in a google search assuming it wasn't a Virtualbox problem. Soon as we can clarify if a reboot with the box unchecked has occurred & hopefully Hakak's guests start working right, we might be able to call in the dogs and put out the fire on this one...

Mpack, I spun up a Windows 10 1903 Enterprise evaluation, and I see that processor checkbox. I don't have 1903 Home version on my house PC yet, wonder if they took it out?

HAKAK wrote:@mpack
A already mentioned several times.

That is twice now you have contradicted me for saying something I did not say. Please do not do it again.

I can read English, so I'm well aware of what OS you are using. My last comment was about the OS's I have available for testing.

scottgus1 wrote: Mpack, I spun up a Windows 10 1903 Enterprise evaluation, and I see that processor checkbox.

Aha, got it thanks, in Win10 Pro (1903 64bit). The OP's screenshot showed the "Start"<obscured> tab opened, so I was looking in the Startup tab instead of the Boot tab.

I just checked a Win10 Home tablet I have, and the dialog is there as well. I've just never noticed it before!

No result.

The list below the checkbox always shows only one processor, even after reboot of the VM.

Would it be helpfull to reboot the whole system, i. e. shuting down all VMs and reboot the host system?
However, this can be done in evening time.

This is the last time I'm going to repeat my request to boot a Linux LiveDVD and see what that gives. After that I'm done here because my advice seems to be ignored...

I believe that this is a misconfiguration of your Win VMs, something that booting into another OS could easily clarify.

After that I'm done here because my advice seems to be ignored..

Sorry.

Download a Linux LiveDVD, for example SystemRescueCD. Boot the Win2016 VM from the LiveDVD, accepting the defaults. Once you're at the terminal, enter the following command which will give you the number of CPUs:

However, I don't have the possibility to do that now, because I can't shut down the machine in the moment, and because I'm working remote on a ssh shell.
I only can do this in the evening (maybe in about 7 to 8 hours).
Can you tell me how I can start the Windows VM from this LinuxLiveCD. Is there any virtualization on it?
Meanwhile I ran nproc on the host system telling me 16
On my samba VM it tells 1
I am a little confused about that
Another question:
The main difference between the both Windows VMs is firmware.
The data I sent are from the EFI one.
The other is BIOS
Does this make any difference for my problem?

HAKAK wrote:Can you tell me how I can start the Windows VM from this LinuxLiveCD

The LiveCD will probably be an ISO download. In the guest settings, click the guest's Optical drive: Click "Choose disk image...", then browse to the downloaded ISO and select it. Now the ISO is attached to the guest's CD drive.
Boot the guest and watch the screen to see how to get to the command prompt so you can type the "nproc" command.