I would recommend you to use the driver posted on this site:
In addition, make sure that the SATA mode has been set for RAID on the system BIOS, on the advanced tab, go to drive configuration and check the configure SATA as... be sure that is set to RAID.
Furthermore, keep in mind that you cannot create a RAID volume bigger than 2 TB to use it for an operating system installation. The operating system will recognize a volume bigger than 2 TB but only for data, not as a bootable unit. if you use all the space on the 4 hard drives you have, the volume would result on 6 TB, which is not a bootable unit, you can create a bootable volume of 2 TB (and install the operating system there) and then use the rest for a data volume of 4 TB
amazing how problems keep coming back with booting and raids 8 years ago i made a 4* 80 gig raid 0 and ran into similar problems. The best way to handle this problem is to make partitions first. The only way i could figure out how to do this is to install windows first on a seperate 5th drive or boot from a backup windows drive/usb you have lying around, boot into windows from the seperate drive/stick, then use windows disk manager to make partitions on the raid drive so you can make a bootable partition on the raid drive. After you made the partitions, remove the 5th drive and install windows on the raid partition you wanted and keep it below 2 terabyte as suggested.
Dont get me started on the install from floppy raid driver isseu haha But i got it working in the end but it takes some dedication and work.
May I make a sugestion , Insteed of making a supper RAID O for your OS Get a SSD Intel makes a real good 160G which is more than enough to hold your OS and all your programs with room to spare ,IT will boot four times faster than any RAID set up.RAID 1 Would be good for your 1.5 TB driver But I'm not sure if you can run RAID and AHCI at the same time, Ive been checking in to it my self so far no joy on answers.