It appears that in Windows 7 some sata ports are incorrectly installed as external ports by default.
A fix can be found in the document located at:
Right Click the command prompt and select 'Run as Administrator';
Copy and paste the following command into the command prompt:
reg.exe add "HKLM\SYSTEM\CurrentControlSet\Services\msahci\Controller(n)\Channel(N)" /f /v TreatAsInternalPort /t REG_DWORD /d 0x00000001
Change (n) for the contoller number – 0 on my machine ie. 'Controller0' and change (N) for the SATA port number – 1 – 5 on my machine ie. Channel1, Channel2, channel3....etc
You can check which controller number and port(s) by using regedit to check the registry keys. The keys can also be be added while your there.