well.
South Bridge:
6 x SATA 3Gb/s connectors (SATA2_0, SATA2_1, SATA2_2, SATA2_3, SATA2_4, SATA2_5) supporting up to 6 SATA 3Gb/s devices
Support for SATA RAID 0, RAID 1, RAID 5, and RAID 10
Marvell 9128 chip:
2 x SATA 6Gb/s connectors (GSATA3_6, GSATA3_7) supporting up to 2 SATA 6Gb/s devices
Support for SATA RAID 0, and RAID 1
GIGABYTE SATA2 chip:
1 x IDE connector supporting ATA-133/100/66/33 and up to 2 IDE devices
2 x SATA 3Gb/s connectors (GSATA2_8, GSATA2_9) supporting up to 2 SATA 3Gb/s devices
Support for SATA RAID 0, RAID 1, and JBOD
by the looks of it, your board has three control chips( each can do RAID) so you need to connect the HDD's to the right SATA ports as listed above under each chip, make sure both HDD are on the same chip, if that makes sense?