Dell OptiPlex Gxi - Manual (Page 12)

Power button On/off push-button that turns computer on and off.
Power indicator Lights up when the computer is on.
Reset button Initiates a hardware reset. To avoid possible data or file structure corruption, use
the reset button only when the system cannot be rebooted with the
key combination, and close any open applications or files if
possible.
Hard-disk drive access indicator Lights up when the hard-disk drive is being accessed.
Diskette-drive access indicator Lights up when the diskette drive is being accessed.