How do I set up RAID on my 680i, 780i, or 790i motherboard?
BIOS Configuration
Go to Standard CMOS Features to verify that your hard drives for the RAID are properly being detected. (Results my vary)
Remember the ports the hard drives are currently located on (A0, A1, B0, etc)
Go to Integrated Peripherals -> RAID Config
Set RAID Enable to Enabled and enable the individual ports for the hard drives that you want to configure in RAID
Press F10 to save the BIOS changes and restart the motherboard.
MediaShield Utility
When asked to, press F10 to enter the MediaShield BIOS Utility. Set the RAID Mode, Striping Block (optional), and move the hard drives from Free Disks to Array Disks.

Press F7 to Finish and your RAID should be configured and displayed as Healthy. Now press CTRL+X to Exit. Your RAID array is now properly configuration and ready.
BIOS settings may vary depending on the BIOS version
Information above obtained from: https://www.evga.com/support/faq/afmviewfaq.aspx?faqid=6&topicid=7