Dell OptiPlex GX260 Series System User's Manual page 139

1 rail tabs (2)
2 second hard drive in upper bay
3 first hard drive in lower bay
4 hard-drive bay
12. Connect a power cable to the drive.
NOTICE: Match the colored strip on the cable with pin 1 on the drive.
13. Locate the extra connector on the drive cable that is attached to your first hard drive and attach the connector to the
second hard drive.
Your computer uses cable-select drive cables. This means that the device connected to the end connector of the drive
cable is the master device and the device connected to the middle connector is the slave device. Be sure that the
jumper setting on the new device is set for "cable select" (see the documentation that came with the drive for
information).
Attaching Cables