Asus P9X79 Deluxe - RAID setup?

First off, I apologize for not having my system specs in my signature. I promise I will get it there shortly. Been meaning to join the forum for ages. Basic info below...

Fractal XL R2 Case (TONS of HD bays open)
MB - Asus P9X79 Deluxe
Processor - Intel Core i7-3930K (3.2, overclocked slightly)
Intel Liquid cooling
Ram - 16GB
GPU - EVGA GTX 570 (have a Galaxy 670 but not supported by my video editing software)
SSD for main OS/software
(2) two - 10k WD Velociraptor drives for scratch disks (video editing)
Rocketraid PCIe Card --> G-Speed eS (6TB, RAID5)

I am completely out of storage and need to consider the next step. I have this MASSIVE computer case (Fractal XL R2) and a good bit of space left on my MB. Ideally I would just pickup a bunch of 2TB drives, put them in the bays, and raid them somehow. I have a Rocketraid card which is running to my current G-Speed RAID (external enclosure), but I would like to avoid spending $1200-$1600 on another enclosure with drives..

So whats the best solution? If setting up a RAID array of drives within the case is possible, is it better/necessary to use the Rocketraid card, or can I go directly through the P9X79 Deluxe board? I thought the P9X79 could run a RAID based on the MB manual, but I want to know if thats the best setup. Speed is not the issue as I am going to run it RAID 5 as my secondary backup/storage.

I am new to setting up RAID arrays, but competent in other technical arenas. Workstations are used only for video editing, no gaming.