supported CX states -- regression?

hello,

when i started on freebsd 5.3 i could see something like the following 
from sysctl:

hw.acpi.cpu.cx_supported: C1/1 C2/10 C3/100

and i remember that my system changed among those states (or at least 2 
of them iirc).

since 5.5 and now on 6.0 all i can see is:

hw.acpi.cpu.cx_supported: C1/1
hw.acpi.cpu.cx_lowest: C1

why is this so, what does it mean and what can i do about it pls ??

regards,

martin