Dell Optiplex SX280 Hard Drive Replacement

Lay the computer on its side; you will see a blue knob.

Turn this knob 90 deg clockwise.

Slide the panel case forward about 1/2 inch while knob is turned.

Lift panel case off computer.

Unplug the blue cable that connects the hard drive to the motherboard.

Unplug the power supply, distinguished by its red and yellow wires (yellow wire obscured from view).

Squeeze the release tabs on either side of the hard drive.

Slide the Hard Drive out while squeezing the tabs.