I have a ASUS Sabertooth X58 Motherboard with SATA3. When Installing Ubuntu using either the Live Desktop X64 or Alt. Install Disk. My SATA3 SSD is not detected (model CTFDDAC128MAG-1G1 2.5). I have changed the BIOS setting from IDE to AHCI to no avail. The disk is also detected during BIOS POST. Is there something that I am failing to do?
Did you set the motherboard to enable RAID support? If you connect your SSD to the SATA2 ports, this will word fine. If the HDD is hooked up to the SATA3 ports, only Grub 2 and Windows 7 will detect it. Ubuntu 10.04 has some problems detecting SSD Sata3 HDDs on some motherboards... It looks like well known.
Here is the mobo's PDF that you can read in section 4.4 about RAID setup. It should guide you through this and should fix the problem.