Hello HamWong,
It is recommendable to install Intel® Rapid Storage Technology when having the chipset mode set as RAID.
Based on the description you provided, I recommend you installing the version 11.7 for testing purposes since you have tested already version 12.5 and 12.0.
You can download the version at the following link:
Another good steps is to test a clean installation and installing all Intel® drivers and Asus driver but not installing the Windows* updates.