Greetings,
First great effort and troubleshooting.
Can I make a suggestion. Simplify your life and get a NAS. You are teetering on hardware that is EOL. Cutting edge in its day but running into resource and compatibility issues trying to use every single available port and slot on your system. Second, are you backing up this data. All I see is RAID 0 and multiple points of failure. Not my business, just an observation.
FD has the support (BIOS level) for disks >2.2TB but you'll have to format GPT for support in windows
FD13 doesn't have BIOS level support for disks >2.2TB on the ICH10r (I believe this is what you confirmed)
And your booting from a PCIe X2 card. Hats off to you sir. Certainly one of the more complex environments I've seen, but unless your protecting that data you've got your pants down.
As far as I can see, you can't do what you want to due hardware limitations/resource issues. A NAS device is one way to solve this problem.