Where is your OP system SATA , IDE HDD1 OR 2?
Sata to sata 1 plug on motherboard,
1 HDD to master and other to slave if on same IDE cable/channel
IF op sys on IDE HDD that that must be master HDD
If OP sys on sata then must be plugged into SATA1 port.
BIOS boot order:
If OP sytem on SATA the boot order is SATA (SCSI), HDD , HDD, CD
IF OP system on IDE then boot order is IDE (HDD)0 , HDD , SCSI (SATA)