Some of the D865PERL boards shipped with a flaky bios - try updating it to the latest (P14). You can get it on the support page for the board, get the IFlash version, not the Express. While you are there, also get the SATA RAID F6 Driver Disk download and use that instead of the one that came with the board, that's the latest, version 3.5.
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Implementation of Serial ATA RAID 1 requires the following items.
* Intel® Application Accelerator RAID Edition version 3.5 or later, and can be found on the Latest Driver Updates page.
* The Intel® Desktop Board D865PERL BIOS must be updated to version P09 or later, and can be found on the Latest BIOS Updates page.
Complete instructions on RAID 0 or 1 installation can be found in the Intel Application Accelerator RAID Edition User's Manual.
http://www.intel.com/support/motherb.../CS-008370.htm