Wired problem about freenas , freebsd , or hardware

[XeR]

Hi everyone , i'm new to freenas.
In last 3 weeks i was busy building my nas.
What i got is a wired problem.

Here is my spec.
Shuttle SB83G5
2X1TB WD HDD
CF TO IDE + 16G CF Card.
2G RAM

FreeNas version : 8.3 / 8.3-p1

First, i use my WD 320G HDD to test the freenas , install freenas 8.3 into the cf card and boot.Everything was fine.
I create a UFS volume , all perfect. But when i reboot the computer. It stall at POST. Waited for 30mins , still showing
Sata-1 WD ***************XX , and i try to press del to go into bios , but fail. I though my old hdd gone.

Then,my 2x1TB hdd arrived , put them on , boot , install freenas 8.3 into cf card again , create a ZFS volume (Raid 1), reboot
and stall at POST.

When i put 3 HDDs into my gaming computer , they all fine . Passed POST and boot into Win7 , no problem.
I tried to put my win7 hdd to NAS computer , it's fine too .

Then i go into bios (without hdd , otherwise i can't go in) . Only i set "Sata Mode" to "Raid" (Ide , ACHI , RAID) can boot.
But a new problem come , i can seeS.M.A.R.T infos.

Please help me~~ Why once i put a hdd into freenas system , i cant even pass the POST?
Thanks a lot!!!