Start by removing the side panel by rotating the blue knob in the direction of the arrow

Remove the floppy drive by pressing the marked knob.

Then pull on the tab that came out of the floppy drive to remove it.

Remove the hard drive by squeezing the two blue tabs on the side.

Then pull the hard drive towards the front of the computer.

Pull out the two cables on the hard drive.

Then lift the hard drive up and out.

Remove the blue cover with 'DELL' on it. by simply pulling it up and out.

Remove the hard drive bracket by unscrewing the two screws.

Slide the hard drive bracket to the left and then towards the front of the computer.

Unplug the connector for the switch. by pressing the little tab on the connector and pulling it up.

And lift the entire bracket out

Unscrew the four screws on the back.

Slide the back plate back, as shown in the picture.

And lift the motherboard tray up and out

Remove both fans by pressing the tab shown in the picture and sliding the fan in the direction shown.

Unplug the connector from the fan by pressing on the little tab on the connector and pulling it up. preferably by the housing of the connector, not the wires.

Pull back the black tab.

Pull the heatsink upwards.

Push down on the lever on the left hand side, and push it to the left.

Lift the lever up

And then lift the bracket up

Remove the CPU by lifting it straight up by the edges of the green PCB.

Remove the RAM sticks by pulling the white tabs away from the RAM sticks.

Pull up and the RAM stick, it should be loose now, if not redo step 1.

Do the same for the second RAM stick.

Remove the heat sink for the graphics chip by pressing the metal tab down and out of the hole.

Unscrew the four screws holding the bracket that holds the heatsink.

Remove the plastic bracket

Remove the CMOS battery by pushing the tab marked in the picture to the left. And the battery will pop out.

Remove the three screws and two standoffs from the motherboard.

Lift the motherboard from the motherboard bracket.

And there you have it, all the components of the Dell Optiplex GX620.