Asus P5M2 User Manual page 24

2. Heartbeat LED (LED1) ( For P5M2/SAS model only )
The green Heartbeat LED blinks per second to indicate that the LSI SAS
1068 chipset has started working.
P5M2/SAS Series HeartBeat LED
This LED is only for the P5M2/SAS model, and it indicates if the LSI SAS 1068
is working normally.
2-2 Chapter 2: Hardware information