HP Pavilion t338d Desktop PC - Manual (Page 127)

upgrading and servicing the pc (1) 119
9 Make sure you attach the connector marked Master on the IDE ribbon cable to
the back of the primary hard drive. After this primary connection is attached,
twist the remaining part of the cable marked Slave on that same IDE ribbon
cable and connect it to the second hard drive.
MASTER
SLA
VE
To CPU
WARNING: Make sure the IDE cable end labeled Master is
connected to the primary hard drive. If you have a second hard
drive, make sure the IDE cable labeled Slave is connected to the
second hard drive. If the IDE cable is not connected correctly, the PC
will not be able to locate the hard drives and data may be lost.