Okay, now I have a new problem... I installed Ubuntu on my new SSD today. But now Windows 8 doesn't show up in the boot loader anymore.
I ran Boot Repair and it told me
GPT detected. Please create a BIOS-Boot partition (>1MB, unformatted filesystem, bios_grub flag). This can be performed via tools such as Gparted. Then try again. Alternatively, you can retry after reactivating the [Separate /boot/efi partition:] option.
Given that it seemed to be the easier option I tried activating the Separate /boot/efi option but Windows does not show up in my boot loader. Even worse, when I try to boot from the Windows SSD via my BIOS it gives me
Reboot and Select proper Boot device or Insert Boot Media in selected Boot device and press a key
So currently I can't get into my windows installation which is my primary and most important drive.
How can I fix this? Do I need to use Gparted? And if so, how exactly? I downloaded the tool but I have no idea what to do here - and I certainly don't want to destroy my Windows installation!