Simple Raid Answer. No problem.
UNPLUG the computer first for safety (don't just shut down). Get a sharpie marker and draw a single line on one sata cable, two on the other. REMEMBER WHERE THEY GO and plug 'em back in.
Actually you could likely get away with mixing up the re-plug but don't test RAID 0. Especially if you end up with the drives on different controllers... cringe.
Good luck. Nice Rig by the way.