Asus P8Z77-V PRO/THUNDERBOLT - Manual (Page 42)

2-18 Chapter 2: Hardware information
Chapter 2
2.2.6 Onboard LEDs
1. POST State LEDs
The POST State LEDs of CPU, DRAM, VGA card, and HDD indicate key components
status during POST (Power-on Self Test). 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 intuitional way to locate the root problem within a second.
2. 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.