Asus P6X58-E WS - Manual (Page 46)

2.6 Onboard LEDs
1. Standby power LED
The motherboard comes with a standby power LED that lights up to indicate
that the system is ON, in sleep mode, or in soft-off mode. This is a reminder
that you should shut down the system and unplug the power cable before
removing or plugging in any motherboard component. The illustration below
shows the location of the onboard LED.
2. POST State LEDs
POST State LEDs check key components (CPU, DRAM, VGA card, and
HDD) in sequence during motherboard booting process. If an error is found,
the LED next to the error device will continue lighting until the problem is
solved. This user-friendly design provides an intuitive way to locate the root
problem within seconds.
You may disable the POST State LEDs in BIOS. Refer to section 3.7.2 Boot
Setting Configuration for details.
2-22 Chapter 2: Hardware information