Insert the drives into the appropriate bays. Make certain that the controller cables and electrical wires can reach each of the drives. Fasten each drive in place with the original screws.
Connect the case control wires to the motherboard. Most cases will have a wire for the PC speaker, reset switch, hard disk activity LED, power LED. Some cases will have wire for the power switch. If there is a wire for "Turbo" it usually serves no purpose and can be ignored.
Install the drive controller ribbon cables to their appropriate drive controllers on the motherboard. Make certain that you align pin #1 of the cables with pin #1 of the controller.
Connect the power supply to each of the drives.
If they were removed, reinstall each of the accessory cards.
If it was connected before, reconnect the CD-ROM sound output to the sound card.
Double check each of your steps.
Reconnect the keyboard, mouse and monitor.
Plug in the power supply and test the PC.
If the system boots properly, shut it down and replace the case. Also reconnect any other wires to the back of the PC.
If there are any problems, the most likely cause is a loose, unconnected or improperly connected card or wire. Shut down and unplug the PC and check all of the connections. If that does not resolve the problem, see our troubleshooting article.