Check if the hard drive has a jumper on pins 5/6, that will also downgrade the speed. Also check if the link below helps.
Jumper settings
http://wdc.custhelp.com/app/answers/detail/search/1/a_id/5387#jumper
Check if the hard drive has a jumper on pins 5/6, that will also downgrade the speed. Also check if the link below helps.
Jumper settings
http://wdc.custhelp.com/app/answers/detail/search/1/a_id/5387#jumper