I have made this test:
- Connect only the SSD on SATA-0 port, but the system not found a disk on boot (press F1 or F2) the bios default is RAID On.
- Configure the bios to RAID Autodetect/ATA and reboot. But the system don't found a drive.
On the box of Samsung SSD I read:
SATA 6Gb/s compatible with 3Gb/s
So:
6Gb/s = SATA III
3Gb/s = SATA II
Where you read that the Samsung 840 120GB is SATA I compatible.
What you see in your BIOS on SATA port? The disk information is not Unknown as my?