You must be running 1.2.3 to see that information, as in 1.2.2 (and very early 1.2.3 builds) there was no support for the chipset in the ALIX in the kernel. It worked, but it didn't know enough to print that line and make the LEDs work, etc.
Without that, it's a bit harder to figure out. You'd probably have to follow this:
http://doc.pfsense.org/index.php/Remount_embedded_filesystem_as_read-write
And add the dmidecode package:
pkg_add -r dmidecode
rehash
dmidecode | more
That should show you information about the system's BIOS