Asus Motherboard P8Z77-M - Manual (Page 29)

1-19 Chapter 1: Product introduction
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.
1.8 Onboard LEDs
2. DRAM LED (DRAM_LED)
The DRAM_LED lights up when the DIMM is not properly installed. Turn off the system
and reinstall the DIMM before using the MemOK! function.