Personal computer hard disk drives usually come in 3.5-inch or 2.5-inch formats. Because of their compact designs, laptops typically use a 2.5-inch hard drive. Such a small drive leaves a chasm of empty space when installed in a desktop computer's 5.25-inch drive bay, which is intended for optical drives. Special railings or brackets bridge the gap between the 2.5-inch hard drive and the sides of the 5.25-inch bay to securely mount the drive. Racks take this a step further by fitting up to four 2.5-inch drives in one 5.25-inch bay.

Step 1

Power down your computer and unplug the power cable. Wait a few minutes for residual power to dissipate from the computer.

Step 2

Open the computer case and connect the anti-static wrist-band from your wrist to the metal frame of the computer case.

Step 3

Remove the bay cover from the 5.25-inch bay. Some bay covers have small clips on the inside that you must release before pushing the cover off from the inside.

Step 4

Align the 2.5-inch hard drive with the inner mounting holes of the bracket. If you're using a pair of mounting rails, align one rail on each side of the hard drive. Racks use smaller, removable brackets that ultimately slide into the rack. If you're using one of these racks, align the hard drive inside the removable bracket.

Step 5

Insert a mounting screw through each mounting hole of the bracket or rail and rotate it clockwise using a Phillips screwdriver until tight. Be careful not to over-tighten the screws. If they feel tight when twisting the screwdriver with just two fingers, it's tight enough. Some brackets, including those used for racks, might have proprietary means to secure the hard drive; check the instructions if you have any doubts.

Step 6

Slide the bracketed or railed hard drive into the 5.25-inch bay and align the outer mounting holes with the mounting holes on the inside of the bay. If you're using a rack, insert the bracketed hard drive into the rack before sliding the rack into the bay.

Step 7

Secure the bracket, rails or rack inside the bay with four mounting screws, two on each side. The screws enter from the outsides of the bay cage and secure to the bracket, rail or rack. You may need to remove both side panels from your tower case to access the mounting holes.

Step 8

Replace the bay cover if the bracket or rack doesn't fill the bay opening.

Step 9

Attach the L-shaped SATA connector from the motherboard to the small L-shaped port on the drive.

Step 10

Connect the L-shaped power connector to the larger L-shaped port on the hard drive.

Step 11

Close the case, plug in the power cable and reboot your system. Windows should automatically recognize your new hard drive.