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[ The PC Guide | Troubleshooting and Repair Guide | The Troubleshooting Expert | Troubleshooting Specific Components | Troubleshooting Hard Disk Drives | Configuration Issues ]

I am trying to get two hard disks to work as master and slave on the same IDE channel, but they don't work together properly the way I want them to

Explanation: You are trying to configure two hard disks on the same IDE channel, with one as master and one as slave, but they are not working together properly. Generally, the system will not boot when they are both in the system, or only one of the drives is recognized by the BIOS. Each of the drives will work individually on the channel. You may find that drive A works as master to drive B as a slave, but drive A can't be a slave to drive B as the master.

Diagnosis: Problems getting drives to cooperate as master and slave are common when using drives made by different manufacturers if either of the drives was designed and manufactured before around 1994. Before this time there was not a generally agreed-upon set of standards for master and slave drives working together on the same channel, and problems were common. With two newer drives, problems with putting them on the same channel points more likely to configuration problems. Problems with two drives from the same manufacturer likewise implicates the drives or their configuration, since the manufacturers weren't generally stupid enough to make their own drives not work together. :^)


  • Double-check the configuration of both drives. Make sure that they are both jumpered correctly and connected to the same channel, that pin 1 of the cable is lined up correctly to pin 1 of the connector on both drives and the controller/motherboard.
  • Independent master/slave device timing is a chipset feature that allows drives on the same channel to be set to different PIO modes. If you are using an older drive with a newer one, and your motherboard does not support independent timing, make sure that both drives are set to use a timing mode no faster than what is supported by the slower drive, or the slow one will not work properly.
  • If the drives are not working together at all, consider changing the order and making the one that was previously the master into the slave, and vice-versa. This may not be acceptable to some people but for others will work.
  • If you are using a manufacturer's brand of dynamic disk overlay (the free software hard disk manufacturers include to allow access to the full hard disk volume on machines without BIOS support for large disks) then you may have a problem when trying to add another manufacturer's large disk to the same IDE channel. The free versions of this software are generally tailored to work with a specific manufacturer's drives.
  • Consider changing the way you set up your IDE devices; see this section for ideas on different ways to set them up. For example, if you have a new, fast hard disk, an older, slow hard disk and a CD-ROM drive, and you can't get the two hard disks to work together on the primary IDE channel, try putting the slow disk with the CD-ROM on the secondary channel. This is in some ways a more optimal arrangement in any event and may solve the conflict.
  • You just may not be able to use the two disks on the same channel. You will be forced to change one disk or the other, or run them on separate channels.

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