Mobo:GA-MA785GT-UD3H (rev. 1.0) with HDD-WD10EARX-Sata3 Issue

My PC:
Model Name : GA-MA785GT-UD3H(rev. 1.0)
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M/B Rev : 1.0
BIOS Ver : F8
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VGA Brand : PowerColor Model : HD5770
CPU Brand : AMD Model : Phenom II x4 Speed : 2800
Operation System : Win 7 32-bit SP1
Memory Brand : Type : DDR3
Memory Size : 2x1GB Speed : 1600
Power Supply : 660 W

Hi all,

I've just installed new HDD-Sata3-6Gb/s-Buffer:64Mb(WD10EARX, 1TB). The Bios just recognize my new HDD 1.5Gb/s(Capabilities) while setting RAID.

This is a picture of Gigabyte manual, and the description-part is my problem.


I tried on jumper setting of my new Sata3-HDD(WD) to set it down with 3Gb/s but the Bios just recognized 1.5Gb/s, too.

I used the other official SATA cable. No change.

And my older HHD-Sata2-3Gb/s-Buffer:16Mb(SeaGate, 320Gb) still recognize this HDD-SeaGate 3.0Gb/s(Capabilities) while setting RAID.

The goal i need to get is, why my mobo can't recognize my new WD-HDD-Sata3 as Sata 3G(see the picture i posted) but Sata 1.5G .

I really need my mobo recognize recognize my new HDD as 3Gb/s(Capabilities) while setting RAID, not Sata1.5G .

Could you please discuss more...
Thanks.