Have you still got Linux partitions present on the hard drive? If so, try deleting them (this by itself does not remove any data so if you recreate these partitions afterwards with exactly the same start/end sectors and types, you will not even have to re-install Linux), reboot Windows just in case, then see whether the option appears again. I have seen at least one case when the presence of any additional data partitions on the HDD prevented activation of acceleration, even though according to what I have seen mentioned on the Web this should not happen if said partitions are not recognised by Windows.
↧