Cpu Warning Led (Errcpu1, Errcpu2); Power Led (P5Vled1) - Asus RS720-E8-RS24-ECP User Manual

3.

CPU Warning LED (ERRCPU1, ERRCPU2)

The CPU warning LEDs light up to indicate failure on either CPU1, CPU2, or both.
4.

Power LED (P5VLED1)

This LED lights up when you turn on the system using the Power-on button.
4-20 Chapter 4: Motherboard Information