Enable AHCI Hard Drive

On my machine I have enabled AHCI drives

I changed a registry setting to 0

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Msahci\Start

http://support.microsoft.com/default.aspx/kb/922976?p=1

In the bios I had to enable SATA AHCI as well as SATA AHCI Legacy

Now it seems to have increased HD speed 50%.