I tried doing this the other night with a pair of 2TB Greens in 0, but I couldn't get Windows to boot when switched from AHCI to RAID, and just did it in Windows instead. Anyone think that there'd be a significant advantage to figuring out how to do it on the chipset?
Going to RAID0... You were converting the OS disk or something?
I'm guessing not, since that would be complicated. If your OS disk is on the same controller, and safe mode doesn't work, see if you have another SATA controller you can use temporarily. A lot of motherboards do, even most, I'd say. I disconnected all but my OS disk, put it on the other controller, booted. Let Windows figure that out. Rebooted, switched from AHCI to RAID. Save, boot, let Windows figure THAT out. Install Intel's RAID utility optionally, for better feedback/control panel. Reboot. Verify one last time that the controller is fully functional and visible in Windows. Shut down. Move OS disk from third party controller to Intel RAID. Boot, see Windows, realize it wasn't that bad, as workarounds go.
But really, the Safe Boot method in Win8 is pretty much Teh Bombz0r. In Windows 7, you can achieve most of the same effect by registry edits.