Asus Z87-C - Manual (Page 34)

ASUS Z87-C 1-26
1. Standby power LED (SB_PWR)
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.
1.7 Onboard LEDs
2. POST State LEDs
The POST State LEDs provide the status of these key components during POST
(Power-On-Self Test): CPU, memory modules, VGA card, and hard disk drives. If an
error is found, the critical component’s LED stays lit up until the problem is solved.