You probably have found the answer, but here is one I gave in a few other threads:
The following Intel® Desktop Boards support hard disk drive (HDD) passwords, but afaik, they only support weak passwords (8 chars), so you should not rely on this feature to protect your data.
Intel® 7 Series Chipset Family Boards
From Intel's motherboard documentation:
"Password can be 2-8 alphanumeric characters in length."