I have the same problem as the OP. I have a pair of Samsung EVO 500ssd in Raid 0. I can boot to my SSHD and see the array in Windows. looks completely intact. I think if the Raid firmware would load at boot, then the OS would not have any problem. The bios says
a) there are not any available drives for a raid array
*AND*
b) there is a raid array
Switching back and forth from ACHI to Raid the system asks if I want to exit without making any changes. If I exit after AHCI > Raid, the raid firmware does not load. It goes directly to the windows boot menu.
It is ridiculous. All it needs to do is load the damn raid firmware, and load the raid array that it identified in advanced setup.
and btw, backup and restore is not a solution. I still have to delete > rebuild > re-install > load drivers > restore from backup.
I have the latest as of 2/6/2015 and it will be the last time I flash an Asus mobo, and it will be the last time I -buy- an Asus mobo. There was no point in spending all that money for speed when rebuilding the system cost more time than I will ever save by running SSD in Raid0. $350 for the mobo + $500 in SSD = $850 in hardware and not to mention my time and frustration.
ASUS can fix it or #*&^ off.