Compaq 239158-999 - Mini Tower - Power Supply 250 Watt Hardware Reference Manual page 48

Hard Drive Installation Guidelines
B-4
Every SCSI chain or circuit must be terminated (closed) at both
ends. Termination can be accomplished through one of the
following methods:
Using a cable with a built-in terminator. This cable was
shipped with your computer.
Using a cable with a terminating resistor plug in the last
connector.
Connecting a SCSI device with its termination enabled into the
last connector.
Connecting an external SCSI device with its termination
enabled to the external SCSI connector on the rear panel of the
computer.
Turn on all external SCSI devices before turning on the power to
the computer. This action enables the SCSI controller to
recognize the external devices.
The system accommodates a combination of internal and external
SCSI devices, such as hard drives, tape drives, and CD-ROM
drives.
Compaq does not recommend mixing different-width SCSI
devices on the same SCSI chain or on the same SCSI channel.
Mixing devices of different widths on the same chain or channel
will always result in the data transfer rate of the slowest device in
that chain. It is acceptable to mix Wide-Ultra2, Ultra 160, and
Ultra 320 devices on a single channel. Do not put narrow devices
on a channel with any device type other than another narrow
device.
For additional information about optional SCSI devices, refer to the
documentation included with the device or contact your Compaq
authorized dealer, reseller, or service provider.
CAUTION: Do not route cables near the air intake to the power supply.
Cables routed in this manner can block airflow to the power supply,
causing it to overheat.
Hardware Reference Guide