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This chapter is from the book

This chapter is from the book

Troubleshooting ATA/IDE Hard Disks

Most computers, whether they’re desktop or notebook, use ATA/IDE hard disk drives as their primary storage. Figure 3.1 shows typical examples of both varieties.

Figure 3.1

Figure 3.1 ATA/IDE notebook (left) and desktop (right) hard disk drives.

What causes an existing ATA/IDE hard disk to "disappear" from the system so you can’t boot from it or access data on it? Any of the following:

  • The hard disk is not connected to power or the power cable is loose. If the hard disk doesn’t have a reliable connection to power, it never spins up and is never detected by your system. During installation of the drive, be sure to firmly connect the drive to a power cable coming from the power supply. If you use a Y-splitter or power cable extender, be sure the splitter or extender is in good condition and is firmly connected to the power cable and to the drive. Take a good look at Figure 3.2 later in this chapter to see the right way to connect the power cable.

  • The hard disk is not properly connected to the ATA/IDE host adapter on the motherboard or add-on card. If the hard disk isn’t properly connected to the interface, it won’t receive the command to spin up when the computer is turned on, and your system won’t boot. The 80-wire cables used by recent hard disks are keyed (see Figure 3.4) to prevent reversed connections, but 40-pin cables and some older systems don’t support keying, making it possible for the cable to be installed upside down at either the host adapter or drive end.

  • Damage has occurred to the signal cable or power cable. Replace cables that have creases across the wires, nicks, cuts or tears, or have cracked or loose connectors.

If you’re installing a new ATA/IDE hard disk but you’re unable to prepare it for use, you can also have problems with power and data cables. Plus, two other possible causes join the list:

  • The hard disk could be configured as "Not present" or "none" in the system BIOS. The drive should be configured using the Auto setting to enable the drive to report its configuration to the system.

  • The drive is not jumpered correctly. The older 40-wire cables require that one drive be jumpered as master and the other as slave; some brands of drives don’t use jumpers if only one drive is on the cable. On the other hand, 80-wire cables use cable select jumpers for both drives, using the position of the drive on the cable to determine which drive is the primary (master) and which the secondary (slave) drive. Now that you know what can cause your system to have problems recognizing your existing or newly installed ATA/IDE hard disk, it’s time to learn how to fix these problems.

Checking the Hard Disk Connection to the Power Supply

Virtually every ATA/IDE desktop hard disk drive uses a 4-pin Molex power connector. The same power connector, by the way, is also used by ATA/IDE optical drives (CD-RW, DVD-ROM, DVD rewritable, and so forth), and a small version is used by some types of ATA/IDE removable-media drives and by floppy drives. If the power connection is not connected to a matching lead from the system’s power supply, the computer will never "see" your hard disk.

Sometimes it’s necessary to connect a Y-splitter to the end of a single power cable to provide power to two hard disk drives or a hard disk and an optical drive (see Figure 3.2). A Y-splitter that’s not well made (thin-gauge wires, not properly insulated) can prevent one or both drives from receiving power.

Figure 3.2

Figure 3.2 A typical ATA/IDE hard drive attached to a Y-splitter power cable before installation into a system.

Whether you connect the hard disk directly to a power supply lead or use an extender or splitter, it takes a bit of force to make a solid connection with the Molex connectors shown in Figure 3.2; make sure the drive is attached solidly to the power cable.

Remember: If your hard disk doesn’t receive enough power, it won’t spin, and your computer won’t know it’s there.

Checking the Drive and Host Adapter Connection to the Data Cable

The second suspect in the "case of the disappearing hard disk" is the data cable. On a desktop computer, the connection between an ATA/IDE host adapter and the drive is made with a 40-pin cable (the cable itself can have 40 or 80 wires, as shown in Figure 3.4). If the cable is not connected correctly to either the host adapter or the drive, the drive will not be detected and cannot be used.

The contrasting-colored markings on the cable indicate pin 1; line up this side of the cable with pin 1 on the drive and the host adapter. In almost all cases, the location of pin 1 is next to the power connector (see Figure 3.3). Most drives also indicate the location of pin 1 on the bottom or rear of the drive.

Figure 3.3

Figure 3.3 Data cable connections to a typical ATA/IDE drive. Pin 1 should be next to the power connector.

What’s to prevent you from plugging in the cable upside down? A few years ago, alas, the answer was "nothing!" A lot of novice hard disk installers goofed up and turned the cable upside down at either the hard disk or the host adapter connection on the motherboard or add-on card. An upside-down cable prevents the PC from sending the spin-up command to the hard disk, and that prevents the hard disk from being recognized. As shown in Figure 3.4, 40-pin cables are typically not keyed, making incorrect installation all too easy.

Figure 3.4

Figure 3.4 An 80-wire keyed ATA/IDE data cable compared to a 40-wire unkeyed ATA/IDE data cable.

If you use 80-wire cables (as you should with today’s hard disks), don’t worry. As Figure 3.4 shows, they’re keyed with a projection on one side of the cable (and sometimes a blocked hole for pin 20) to prevent incorrect installation.

A data cable is useless unless it’s connected to a host adapter. The ATA/IDE host adapter is usually on the motherboard. Figure 3.5 shows how to attach an 80-wire cable to the host adapter. Note the markings for pin 1 on the motherboard and how the keyed cable prevents incorrect installation. There are usually two ATA/IDE host adapters, and some computers have more. Use the lowest-numbered host adapter for your system hard disk.

Figure 3.5

Figure 3.5 An 80-wire ATA/IDE cable properly attached to the host adapter on the motherboard.

Configuring ATA/IDE Drive Jumpers

When you took the PC tour that’s the highlight of Chapter 1, you might have been surprised to discover that an ATA/IDE cable can support two drives. When you install a new ATA/IDE hard disk or other drive, how does the computer tell which drive is which?

Unlike a floppy drive cable, which uses a twist at the end of the cable to indicate drive A: and drive B:, an ATA/IDE cable is a straight-through cable. An ATA/IDE drive is configured as master or slave with jumper blocks on the rear or bottom of the drive. The position of the jumper blocks and the type of cable used determines which drive is the primary (master) and which the secondary (slave) drive. These jumpers are used in the same way on any ATA/IDE device, including optical and removable-media drives.

ATA/IDE drives have three basic configurations that can be selected with jumper blocks (see Figure 3.6):

  • Master (MA)

  • Slave (SL)

  • Cable Select (CS, CSEL)

Figure 3.6 shows the most common jumper location and the various jumpering options supported on a typical hard disk.

Figure 3.6

Figure 3.6 The jumper pins and jumpering options available for Western Digital hard disks.

Other brands of hard disks use slightly different jumper block configurations; be sure to follow the labeling or instructions for the particular hard disk you are installing or troubleshooting.

Different jumper settings are recommended for 40-wire and 80-wire ATA/IDE data cables. Table 3.2 helps you figure it out.

Table 3.2 Correct Jumper Settings for a New ATA Drive Installation

Cable Type

Drive Installed As

How to Jumper

Which Cable Connector to Use

Jumper Original Drive As



Cable Select or Slave

Gray connector (middle of cable)

Cable Select or Master1


Only drive on cable

Cable Select, Master, or single drive1

Black connector (end of cable)




Cable Select or Master1

Black connector (end of cable)

Cable Select or Slave1







Only drive on cable

Master or single drive (check drive manufacturer recommendation)








1. With 80-wire cables, we recommend you try Cable Select first. If you have problems with drive recognition, use Master or Slave settings as shown in the table. Drive recognition issues are more likely if you are mixing different brands of drives on the same cable.

Here’s how to apply these settings when you install a new hard disk or other ATA/IDE device:

  • Master/slave—A drive jumpered as master will be the primary drive on the cable; if you have your hard disk and optical drive on the same cable, the hard drive should be jumpered as master, and the cable should be plugged into IDE connector number 1 on the motherboard.

  • Slave—A drive jumpered as slave will be the secondary drive on the cable. If you have your hard disk and optical drive on the same cable, the optical drive should be jumpered as slave.

  • Cable select—The position of the drive on the cable determines which drive is master and which is slave; Cable Select requires an 80-wire Ultra ATA cable. Some computer vendors use specially designed 40-wire cables that support Cable Select. Note that you can also use Master and Slave settings with 80-wire cables.

Checking a Laptop/Notebook’s Hard Disk Power/Data Connection

We mentioned earlier in this chapter that a laptop or notebook computer’s 2.5-inch hard disk drive uses a single 44-pin connection for power and data. The hard disk might plug into a fixed power/data connector or a flexible cable.

If you actually use your laptop or notebook as a portable computer and move it around frequently, the hard disk’s connection to the notebook’s motherboard could become loose, causing the hard disk not to be recognized at startup.

If the hard disk is accessed through a removable cover on the bottom of your portable computer, you can follow this procedure to check the connection:

  1. Shut down your computer.

  2. Unplug it.

  3. Turn over your computer.

  4. Use a small screwdriver to remove the retaining screw holding the cover and the hard disk in place. Figure 3.7 shows the relationship of the retaining screw and the hard disk as seen from the hard disk drive bay.

  5. Figure 3.7

    Figure 3.7 Detail view of a 2.5-inch ATA/IDE hard disk and its retaining screw.

  6. Slide the hard disk out of the computer.

  7. Reinsert the hard disk, making sure it connects tightly to the host adapter power/signal connector in the drive bay. Figure 3.8 shows a top view of the hard disk, retaining lug, and host adapter connector.

  8. Figure 3.8

    Figure 3.8 Reinserting a portable computer’s hard disk into the drive bay and host adapter.

  9. Close the access cover.

  10. Reinsert the retaining screw.

If you need to install a replacement hard disk in a portable computer, see "Upgrading a Portable Hard Disk," this chapter, for complete instructions.

If the hard disk cannot be accessed from the bottom or side of your portable computer, check the manual or the manufacturer’s website to learn how to check the hard disk connection. You might need to remove the keyboard or other components to get to the hard disk.

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