Dell OptiPlex 745c (Early 2007) - Manual (Page 61)

Most interface connectors are keyed for correct insertion; that is, a notch or a missing pin on one connector matches a tab or a filled-in hole on the other
connector. Keyed connectors ensure that the pin-1 wire in the cable (indicated by the colored stripe along one edge of certain cables—SATA cables do not use
a colored stripe) goes to the pin-1 end of the connector. The pin-1 end of a connector on a board or a card is usually indicated by a silk-screened "1" printed
directly on the board or card.
Power Cable Connectors
Connecting and Disconnecting Drive Cables
When removing an cable with a pull-tab, grasp the colored pull-tab and pull until the connector detaches.
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. Check the documentation for the drive to verify that it is configured for your computer.
3. Follow the procedures in Before You Begin .
4. Disconnect the power and data cables from the drive.
1 interface cable connector 2 interface connector
NOTICE: Inserting a cable incorrectly prevents the drive from operating and could damage the controller, the drive, or both.
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.