Maxtor 133 => only show Ultra Mode 5 ?

Ok...
Why in my computer property only shows that my HD only Ultra mode 5 instead of 6? Yes, in the bio when i boot up it says that ATA 133.
I remember it showed mode 6 now it is only mode 5.
And this is only HD that i'm running for testing rite now.
Thank you.

bump, no1 knows why?