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If you like to add second drive and create RAID 0, Intel® Rapid Storage does not automatically create RAID array. You need to open Intel® Rapid Storage and modify your configuration.
Please check Intel® Rapid Storage user's guide: http://download.intel.com/support/chipsets/imsm/sb/irst_user_guide.pdf
After you add it and then activate it does it stripe it then.
I am not quite sure to understand your feedback. Please provide more detailed information. If you need live support for RAID issues, please go here: Contact Support then select Chipset software support.