Dell DCSM manual Back View of the Computer

		connector	voice or musical input into a sound or telephony program.
			On computers with a sound card, the microphone connector is on the card.
7		headphone	Use the headphone connector to attach headphones.
		connector
8		diagnostic	Use the lights to help you troubleshoot a computer problem based on the
		lights (4)	diagnostic code. For more information, see "Diagnostic Lights."
9		hard-drive	The hard drive activity light is on when the computer reads data from or
		activity	writes data to the hard drive. The light might also be on when a device such
		light	as a CD player is operating.
10		power	Press the power button to turn on the computer. The power light in the center
		button,	of this button indicates the power state. See "Specifications" for more
		power light	information.
			NOTICE: To avoid losing data, do not use the power button to turn off the
			computer. Instead, perform an operating system shutdown.
11		USB 2.0	Use the front USB connectors for devices that you connect occasionally, such
		connectors	as joysticks or cameras. It is recommended that you use the back USB
	(2)		connectors for devices that typically remain connected, such as printers,
			keyboards, and mice, or for bootable USB devices, which may not function
			properly if attached to the front connectors.
12		vents	For adequate cooling, do not block any of the vents.

NOTICE: Ensure that there is a minimum of two inches of space between all vents and any object near these vents.

NOTICE: Do not lift or carry the computer by the vents to avoid damage to the computer.

NOTICE: Keep the vent area clean and dust-free to ensure that the computer is adequately ventilated. Use only a dry cloth to clean the vent area to avoid water damage to the computer.

Back View of the Computer