How to fix Ubuntu showing only one core?

I have installed Ubuntu after long struggle. The complete details is available in below link.

https://ubuntuforums.org/showthread.php?t=2465857

Now I am facing issue with only one core and one CPU. so the system is ultimate slow.

I have tried below options, but no luck

1. adding only pci=nocrs, system not booting.
2. adding acpi=off pci=nocrs, same result
3. adding acpi=ht, system not booting.

Screenshot for reference: Any suggestions?

There are generally two items that need to be done for this processor; installing the amd64-microcode package for the cores and setting nomodeset in the boot options for the video.

First, let's make sure the APU's microcode is properly installed:

1. Open Terminal
2. Update apt:

   sudo apt update 
   

3. Install the microcode:

   sudo apt install amd64-microcode
   

4. Reboot

Once the machine completes its boot cycle, check the system monitor (or use another tool) to confirm that four CPU cores are found.

At this point, you may notice poor video performance. This is generally resolved by adding nomodeset to your boot options:

1. Open Terminal
2. Open the /etc/default/grub file with sudo using an editor of your choice. For example:

   sudo vi /etc/default/grub
   

3. Find the line that starts GRUB_CMDLINE_LINUX_DEFAULT and add nomodeset to the end (inside the double-quotes). For example:

   GRUB_CMDLINE_LINUX_DEFAULT="quiet splash nomodeset"
   

   _{Note: The order of the options is irrelevant, so there is no need to worry about which one comes before another.}
4. Save the file
5. Update Grub:

   sudo update-grub
   

6. Reboot

This should be all you need to do to have access to all four compute cores and the six graphics cores.