Dell OptiPlex 740 - Manual (Page 109)

Interface connectors are keyed for correct insertion.
Power Cable Connectors
Connecting and Disconnecting Drive Cables
When connecting and disconnecting a SATA data cable, hold the cable by the black connector at each end.
Hard Drive
Removing a Hard Drive
1. If you are replacing a hard drive that contains data you want to keep, back up your files before you begin this procedure.
2. Follow the procedures in Before You Begin .
3. Disconnect the power and hard-drive cables from the drive.
Serial ATA Power Connector
1 power cable 2 power input connector
CAUTION: Before you begin any of the procedures in this section, follow the safety instructions in the Product Information Guide.
CAUTION: To guard against electrical shock, always unplug your computer from the electrical outlet before removing the computer cover.
NOTICE: To avoid damage to the drive, do not set it on a hard surface. Instead, set the drive on a surface, such as a foam pad, that will sufficiently
cushion it.