Yes, it is possible to boot Windows from a separate disk using GRUB. Here are general steps: 1. Install Windows on your SATA SSD. 2. After installing Windows, boot into your Ubuntu installation. 3. Open a terminal and update the GRUB boot entries by running `sudo update-grub`. This command should detect all the OS installations on all attached drives and add them to the GRUB boot menu. Here's the explanation: `sudo` allows you to run commands as the root user, `update-grub` is a script that uses `os-prober` to detect OS installations and regenerate the GRUB configuration file (`/boot/grub/grub.cfg`), populating it with entries for each OS it finds. Things to note: 1. Ensure Secure Boot is disabled in your BIOS settings as GRUB might not be able to boot Windows if it's enabled. 2. If GRUB still doesn't show the Windows boot option even after running `sudo update-grub`, manually add a custom menu entry for your Windows installation in the `/etc/grub.d/40_custom` file. 3. Always backup your data before making these changes. It's unlikely, but things can go wrong. 4. If you install Windows after Ubuntu, Windows might override the MBR and might not recognize Ubuntu. You might need to repair your grub. Good luck, and remember: Always make backups before making significant system changes.