Setting disk "compatibility" mode

[Mortdk]

Hey folks,

I gave my T23 a hard disk upgrade a while ago. I remember having to set the hard disk drive to compatibility mode or else it wouldn't boot.

Well - it worked. Then the T23 died (unrelated to the disk upgrade), but I have now revived it! Bios has been reset, and now I cant find / remember where to set the compatibility mode. Somewhere in the bios? I must be blind - cant find it!

Any help?