I just upgraded my T3400 to Windows 7, and am having an intermittent problem with the RAID controller: Sometimes when I boot the machine, the RAID Option ROM reports a RAID array as "Degraded" and the corresponding list of drives shows that a drive is missing.
I took the BIOS out of "Fast Boot" mode and the problem went away. I think that what is happening is that the BIOS is handing control over to the RAID Option ROM before the disks have completely spooled up, and it is therefore failing to detect one or more of the disks.
I realized at some point that I had the "SATA Operation mode" option in the BIOS set to "RAID On," and the system default is "RAID Autodetect/AHCI." I've set the option back; but I wonder whether anyone else out there has had a similar problem, and, if so, how they resolved it.