Create a 100GB partition for the system. (It will make a 300MB partition also automatically just ignore it) and then the rest for DATA. Example on a 1TB you make 100GB for W8 and 800GB. What the big deal with this? Well if you had W8 you probably had many problems then deleted it all after backing your DATA up. With this little trick you won’t have to delete your DATA. Just reinstall W8 in your 100GB partition.
Next time you install Windows 8 or 10 or whatever do this.