One beep - board is working fine
One long beep then machine shuts down - faulty, improperly installed or missing CPU
1 short(Beep) System booting is normally
2 short(Beep) CMOS setting error
1 long - 1 short(Beep) DRAM ERROR
1 long - 2 short(Beep) Display card or monitor connected error
1 long - 3 short(Beep) Keyboard Error
1 long - 9 short(Beep) ROM Error
Long(Beep) continuous DRAM isn't inserted correctly
Short(Beep) continuous POWER supply has a problem
A two-tone siren, generally caused by overheating or out of specification voltages