My Computer Won't Recognize My Second Hard Drive
As long as your secondary hard drive is properly configured and plugged into both the motherboard and the computer's power supply, then the Basic Input/Output System (BIOS) will autodetect it. However, BIOS cannot autodetect a dead hard drive. This information narrows down your troubleshooting tasks to cable-checking. For most modern computers, this is as simple as making sure everything is plugged in. If your computer is older and uses Integrated Drive Electronics (IDE) drives, only then does cable-checking become difficult.
Reboot your computer and press the setup key before Windows boots. The setup key is typically "Esc" or one of the function keys. Wait for BIOS to load and then look for two hard drives in the hardware list that appears. If your secondary drive did not appear at all from within Windows, then it likely will not appear in BIOS either. Shut down the computer and unplug it from the wall.
Open up the computer and look for the hard drives. Hard drives are typically housed in a metal "cage" located towards the front of the computer and underneath the optical drives. Check the back of the hard drive. There should be two cables attached to the back. If you find no cables attached, or only one, find cables that match the primary drive's cables and reattach them to the back of your secondary hard drive. If you do find both cables attached, remove and reattach them, just in case they were incorrectly attached.
Determine if your computer uses Serial Advanced Technology Attachment (SATA) hard drives or if the drives are Integrated Drive Electronics (IDE). The data cable on a SATA drive is about 1/4-inch wide and usually red in color. An IDE drive uses a 2-inch wide cable, usually grey in color. If your drives are IDE, then it is possible your hard drives are using incorrect jumper settings.
Correct the jumper settings on the IDE drives, if any are present. Different hard drive brands use their own jumper schemes, so read the jumper diagram on the hard drive's label. For two IDE drives to share one cable, the drive attached to the very end of the cable requires a "master" setting, and the next drive down on the cable requires a "slave" setting. When each drive uses its own cable, you must set both of them to "master." To change the setting, pull the jumper off the two pins it is already covering and connect it to the correct pins, as shown by the diagram on the drive.
Check that the data cable connected to your secondary hard drive is attached to the motherboard. If the cable is not attached, attach it to the motherboard in a compatible socket. This socket is located next to the one to which your primary drive is connected.
Plug your computer into the wall and power it on. Boot into BIOS and then look for your secondary drive in the hardware list. This time, if your computer still does not see the secondary hard drive, there is a chance that it is dead. Check the cables once more, but if that does not work, take the drive out and replace it with a new one.