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ref - http://www.asus.com/Motherboards/AMD_AM2Plus/M4A78/#specifications

5 xSATA 3 Gb/s ports Support RAID 0,1,0+1,JBOD

*Due to the Windows XP/ Vista limitation, the RAID array with the total capacity over 2TB cannot be set as a boot disk. A RAID array over 2TB can only be set as a data disk only. For more information, please refer to http://support.microsoft.com/kb/946557/en-us

Before going through your manual a question and statement. First, never RAID 0 your HDD/SSD if anything important is on them e.g. Documents; in RAID 0 IF either drive fails you instantly lose everything on them for good. RAID 1 offers no measurable speed gain and the drives are 'mirrored' aka cloned.

Q - What type of RAID? {0,1,0+1}
Q - What drives and size?