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The tests performed were with new drives?
What is the exact status of the RAID?
You may also try this, access the RAID BIOS (Ctrl + I) and choose “Reset Disk to non-RAID” (for both drives if needed). When you do this you will get a message warning you about data loss, in most RAID types this will be true but there is no problem with RAID 1, since it is a mirror the data will remain.
Now, in order to create the RAID 1 again without losing the data you will need to boot into Windows*, start Intel® Rapid Storage Technology, and create the RAID volume from the drive with existing data, as explained in the user guide (page 30). This option does not appear in the RAID BIOS, therefore creating the RAID volume there will delete the data.