Alienware Aurora - disable raid 0

Hi all,

My Alienware Aurora has 2 HDD in RAID 0, and as I'm going to reinstall everything on it I would like to change it to 2 separate drives. Just in case one drive fails, at least I won't loose all my data...

However, I've been struggling to manage to disable it. I went in the bios and set the following

Configure SATA#1-6 as - AHCI (was RAID before)

OptionROM Display Screen - Display (was hidden)

The problem is that when I try to reinstall windows, only one of the 2 HDD is listed when I have to select "Where do you want to install windows", and selecting the hard drive (even after deleting/recreating/formatting the partition) results in the following message: "Setup was unable to create a new system partition or locate an existing system partition..."

If I do not configure SATA#1-6 as AHCI but leave it as raid, then I can reinstall windows without any problems...

Any idea?

Cheers