Installing a new hard disk is one of the most common upgrade tasks. It’s an easy way to extend the life of a computer that is running out of storage space. When you install a new internal or external hard disk, you can boost your total disk space several times over because hard disks are much bigger today than just two or three years ago.

External hard disks

The simplest way to add more hard disk space is to plug in an external hard disk. If you add an external hard disk, it can't function as your primary hard disk where you install Windows, but you can use it as a secondary disk to store programs and files. Adding an external hard disk is a good way to create plenty of extra space to store digital photos, videos, music, and other files that require a large amount of disk space.

To install an external hard disk, all you have to do is plug it into your computer and connect the power cord. Most of these hard disks plug into a USB port, but some plug into a Firewire (also known as IEEE 1394) or external Serial ATA (eSATA) port. For additional instructions, check the information that came with your external hard disk. You might also need to install any software that came with the hard disk.

For more information, see Install a USB device.

Illustration of a typical USB cable and port
You can install most external hard drives just by plugging them into a USB port.

Internal hard disks

Internal hard disks connect to your computer's motherboard using an IDE interface or SATA interface. Most new hard drives come with either an IDE or SATA connection cable, depending on the type of drive.

Installing an internal hard disk takes a bit more work, especially if you plan to make the new disk your primary hard disk where you install Windows. To install an internal hard disk, you should be comfortable opening your computer case and connecting cables.

Most desktop computers have room for at least two internal hard disks. Laptops have room for only one hard disk. If you are replacing the primary hard disk rather than adding a secondary disk, you'll have to install Windows after you connect the disk.

Note

  • Many internal hard disks contain jumper pins that you must set to designate a hard disk as a primary (master) disk where you install Windows or as a secondary (subordinate) disk where you store programs and files. These jumpers are small plastic sleeves that you must place on the correct metal jumper pins. For additional instructions, check the information that came with the internal hard disk.

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To remove and replace an internal hard disk

  1. Turn off your computer, disconnect the power, and remove your computer’s cover. If you have a laptop, check the information from the manufacturer to find out if there is a panel you can remove to access the hard disk.

  2. Unplug all cables connected to the hard disk, and then remove the hard disk. Pay attention to which cables you unplug, since you will plug the same cables into the new hard disk. If there are any screws holding in the hard disk, you'll need a small screwdriver to unscrew them. Many hard disks slide in and out of the case on rails. If you have questions, check the information that came with your computer.

  3. Insert the new hard disk and connect it to the same cables that are in the same places as the hard disk you removed. One cable connects the disk to the computer’s power supply, and the other cable connects the disk to the computer’s motherboard.

To add a new internal hard disk (without removing an existing disk)

  1. Turn off your computer, disconnect the power, and remove your computer’s cover. If you have a laptop, check the information from the manufacturer to find out if there is a panel you can remove to access the hard disk.

  2. Insert the new hard disk into an empty hard disk bay in your computer case. You might need a small screwdriver to screw the disk into your case. Different cases have different ways of holding hard disks. Many slide in and out of the case on rails.

  3. Connect one cable from the computer’s power supply to the power connector on the back of the hard disk.

  4. Depending on what type of hard disk you have, connect the IDE cable or SATA cable from the back of the disk to the IDE or SATA connector on the computer’s motherboard. IDE cables are wide and flat with large connectors, while SATA cables are thin with small connectors. For more information, check the information that came with the hard disk.

Preparing to use a new hard disk

If you've installed your new hard disk correctly, your computer should recognize it. When you turn on your computer, the basic input/output system (BIOS) should automatically detect the new hard disk.

If you plan to use the new hard disk as the primary partition that contains Windows, then you'll have to install Windows on the disk before you can use your computer. You'll need a Windows 7 installation disc to do this. For more information, search Help and Support for "Installing and reinstalling Windows."

If you plan to use the new hard disk as a secondary disk (one that does not contain Windows), you should be able to see the new hard disk drive the next time you start your computer and log on to Windows. After Windows starts, click the Start button Picture of the Start button, click Computer, and then look for your new drive. The letter assigned to the drive will depend on your computer’s configuration. If you don't see the new hard disk drive, try looking for it in Computer Management.
  1. Open Computer Management by clicking the Start button Picture of the Start button, clicking Control Panel, clicking System and Security, clicking Administrative Tools, and then double-clicking Computer Management. Administrator permission required If you're prompted for an administrator password or confirmation, type the password or provide confirmation.

  2. In the left pane, under Storage, click Disk Management, and then look for the new drive.

You'll probably have to format the hard disk before you can use it. For instructions, see Formatting disks and drives: frequently asked questions. Follow these same instructions to format an old hard disk that contains data you want to erase.

If your computer doesn't recognize the new hard disk, double-check the installation instructions that came with the hard disk. If you have additional questions, go to the manufacturer's website.

Note

  • You can divide a new hard disk into more than one partition. Each partition on the hard disk can be formatted and assigned a drive letter. For more information, see Managing hard disks: recommended links.