Asus ESC500 G3 - Manual (Page 58)

Chapter 3: Motherboard information 3-10
7. +12V_PWR LED
The ASUS Dr. Power LED near the EATX12V connector lights up when the ASUS Dr.
Power switch setting is turned to enable and there is no power detected going into the
processor.
8. CPU warning LED (CPU_PWR_ERR)
The CPU warning LEDs light up to indicate an impending failure of the corresponding
CPU.