Acer Altos R720 Series - Manual (Page 156)

5 Troubleshooting 146
Error beep codes
BIOS POST error beep codes
The following table lists the POST error beep codes. Prior to system
video initialization, BIOS uses these beep codes to inform you of error
conditions. The beep code occurs only when a critical error occurs or
when the BIOS fails to boot to the operating system. Not all error
conditions are supported by the BIOS beep codes.
Number
of Beeps
Description
1, 2, or 3 Memory error
4 – 7 or
9 – 11 Fatal error indicating a possible serious system problem
8 Video error