And I still refuse to update from Windows 7 to Windows 10 however certain applications are just running now on Windows 10, even some Wifi PCi cards do the same so for the time being I want to have a dual boot Windows 7 + Windows 10 machine.

So lets get to it.

You’ll need the following:

  1. One extra Hard drive, preferably an SSD and a Caddy adapter so you can fit it onto your HP hot slot quickly if you need to remove it.
  2. One 8GB minimum USB memory (USB 3 preferred but Z800 only has USB 2)
  3. Windows 10 Iso image from here: https://www.microsoft.com/es-mx/software-download/windows10
  4. Download media creation tool and when prompted select Upgrade another computer/Create ISO/Save the iso on your PC
  5. Get Rufus USB Bootable maker tool https://rufus.ie/
  6. On Rufus select the ISO from Windows 10
  7. Select partition Scheme MBR and target system BIOS

After that’s done, get the USB on your HP z800 reboot and make sure that boot from USB drive is enabled.

Run windows install normally, if you have multiple hard drives, make sure to delete the partitions for the drive you’re going to use as system drive for windows 10 this is to avoid the Windows cannot be installed to this disk GPT error.

Et voilá, if you need to select the order, go to msconfig and under BOOT make sure you have both operating systems listed.