I think Bochane is correct; RAID 1 won't work on secondary drives only without including the System Drive (
C: drive).
That's because drive Mirroring was designed to backup your boot drive should that drive crash due to mechanical or electrical failure, and of course with no boot drive, you have no Windows.
Better solutions would be to purchase a
2nd SSD 500GB drive, install that as your secondary drive and attempt to use your Mobo's RAID implementation there. I'm not sure how well SSD's do with RAID, as I have not experimented with them due to their high cost.
Some of the other guys here might be able to chime in if they have personal experience with that however. But there are lots of articles out there. Since you mentioned you wanted to do RAID with your 2 large 5TB drives, I'm guessing you have lots of data that needs to be backed up and protected that won't fit on a small 500GB boot drive
*by the way, that's what I have on my Dell desktop here* as my main production machine.
My Mobo is a Dell OEM and is 8-1/2 yrs. old and it's not capable of doing RAID 1. I can do automatic software RAID1 mirroring using my Macrium Reflect. (I did this when my PC was still running Vista). But, my 2nd 500GB drive is failing and it needs to be replaced; so I'm not currnently running in automatic mode; I do manual Clones to that 2nd drive quarterly.
My solution for large capacity (larger than 1TB) was to purchase a NAS setup, the WD Cloud Mirror solution, which uses 2 drives in a Raid 5+1 or Raid 6 setup. It sits on my home network (LAN) and I can access from any of my 10 computers via the network whenever I need to upload backups or download them for rebuilds.
My primary storage is to keep Customer Image Backup files so I can rebuild their computers much faster if I've previously rebuilt them and they crash due to HDD failure or they scramble them with a nasty Ransomware virus like
NEMUCOD, or
Cryptolocker. These files vary is size from about
9GB to 260GB and thus take up scads of room. The NAS is a perfect low-cost solution.
And you don't have to buy a new Mobo to use it; so the money you spend on a NAS to work with your existing Mobo and setup is not much more than buying a more expensive Mobo that includes RAID5 or 10 capability; not to mention you might have to upgrade your PSU, RAM sticks, Cooler, etc. and other components to work with a new Mobo.
I paid about
$400 for my
WD MYCLOUD NAS a few months ago and I love it!
It's
8TB (2x4TB drives); as is close to what you are looking for. Their next size up is a
12TB (2x6TB drives) which should cover your requirement (5TB), and it's really easy to swap out a drive if you lose one, with the easy eject setup.
Here's a link for you: Amazon.com: WD 12TB My Cloud Mirror Personal Network Attached Storage - NAS - WDBWVZ0120JWT-NESN: Computers & Accessories This link is for the
12TB NAS, mine is the
8TB NAS, but you can go bigger if you want, they have a 16TB NAS on the same link page for a bit more, and I believe if you step up to their
4 drive NAS, you can go to
64TB NAS; which should be plenty of capacity for you.
You can always use those stand-alone 5TB's somewhere else, on another computer, or sell on ebay and get some money to help pay to purchase your NAS.
They are not as good as SANs *which I used to help build*, but for home use they are really nice!
P.S. I like the specs on your ASUS Prime Mobo. Looks like a good board. I'm looking at Mobos as I'm building a new Gaming PC with my son. Best of luck,
<<<<BIGBEARJEDI>>>>