I don't have this board, so my suggestion is based solely on experience elsewhere. I see your board has a Silicon Image controller for SATA 5-8. What the manual says would certainly lead you to believe that the only option for these ports is to use them as a RAID system. And I agree with you that you do not want that if you don't understand RAID. My odd experience with an ASUS board was that, even though the manual talked endlessly about how to set up RAID on my Silicon Image controller chip, it did NOT have to be used as a RAID controller. It still had to be Enabled in BIOS, and I'm sure Windows will want drivers loaded to use it, maybe even drivers labeled as RAID drivers. But once those were done, the BIOS options also included using the SATA port on that controller to run a plain native SATA device, and the drivers for that already had been included in the "RAID" driver package!
Assuming you have one or more SATA drives attached to those mobo ports, you can try Enabling RAID on the SATA ports 5-8 in your Genie BIOS page and then loading the RAID drivers in Windows. When you reboot one of the boot messages / options will be to set up the RAID system on SATA 5-8. Go in there and look around. Unless you specifically choose drives to put into a RAID array and to confirm array creation, it will not steal your disks to make into RAID. After looking for the menu choices, just make sure you have not chosen to create a RAID array and exit out of there and finish booting into Windows. Then start looking for those drives as if they were simply normal independent drives. I fully expect they will NOT show up in My Computer, because new empty drives always need some preparation for Windows to use them. BUT if you go into Disk Manager (which is where the preparation happens) they should show up in the lower right pane (it scrolls to see everything) as hardware devices that are recognized, but not yet available for Windows to use. If the new one(s) are there with the right size (and number of drives, if more than one) you can do the Partition and Format operations needed. Or, you can back out and use software utilities from the HDD maker to get the drive(s) ready to use.
We're curious, so post here what happens as you proceed.