Am I correct that you want to see a single 8TB HDD space?
If you are using windows 7 / 8 / 10 you can do this.
When installing windows on the first HDD, partition off 100GB for OS and other stuff, they rest you can use for a single storage space.
There is no redundancy using raid 0 so if one drive dies you will loose all your data.
Hopefully I am not on the wrong wavelength.
Use storage spaces. DONT use the built in Windows software raid (via disk management). This is on Windows 8, 8.1 and 10