Continuous beeping sound

Do you get video? If so then it could be a stuck key on the keyboard.

Do you get no video? If so then reseat the RAM.

Beep Codes: what they mean
American Megatrends (AMI BIOS)
1 beep: Memory refresh timer error - RAM problem.
2 beep: Parity error in base memory (first 64KB block) - RAM problem.
3 beep:Base memory read/write test error - RAM problem.
4 beep: Motherboard timer not operational - motherboard problem.
5 beeps: Processor error.
6 beeps: 8042 Gate A20 test error (cannot switch to protected mode) - motherboard (keyboard controller chip), keyboard or processor problem.
7 beeps: General exception error (processor exception interrups error) - processor or motherboard problem.
8 beeps: Display memory error (video adapter problem) - check/re-seat video card.
9 beeps: AMIBIOS ROM checksum error - System ROM BIOS problem, re-seat or replace chip, try re-flashing BIOS or swap motherboard.
10 beeps: CMOS shutdown register read/write error - motherboard problem.
11 beeps: Cache memory test failed - Check motherboard jumper settings, if possible replace RAM cache, possible CMOS, processor or motherboard problem.
Phoenix up to version 4.x
Beep pattern
1-1-2: CPU test failure
Low 1-1-2: System board select failure
1-1-3: CMOS read/write error
Low 1-1-3: Extended CMOS RAM failure
1-1-4: BIOS ROM checksum error
1-2-1: PIT failure
1-2-2: DMA failure
1-2-3: DMA read/write failure
1-3-1: RAM refreshy failure
1-3-2: 64KB RAM failure
1-3-3: First 64KB RAM failure
1-3-4: First 64KB logic failure
1-4-1: Address line failure
1-4-2: Parity RAM failure
1-4-3: EISA fail-safe timer test
1-4-4: EISA NMI port 462 test
2-1-1 through to 2-4-4: 64KB RAM failure
3-1-1: Slave DMA register failure
3-1-2: Master DMA register failure
3-1-3: Master interrupt mask register failure
3-1-4: Slave interrup mask register failure
3-2-2: Interrupt vector error
3-2-3: Reserved
3-2-4: Keyboard controller failure
3-3-1: CMOS RAM power bad
3-3-2: CMOS configuration error
3-3-3: Reserved
3-3-4: Video memory failure
3-4-1: Video initialisation failure
4-2-1: Timer failure
4-2-2: Shutdown failure
4-2-3: Gate A20 failure
4-2-4: Unexpected interrupt in protected mode
4-3-1: RAM test failure
4-3-3: Interval timer channel 2 failure
4-3-4: Time of day clock failure
4-4-1: Serial port failure
4-4-2: Parallel port failure
4-4-3: Math co-processor failure
Phoenix from version 4.x onwards
Beep pattern
1 short beep: everything OK and booting normally.
1-3-1-1: RAM problem.
1-3-4-1: RAM problem.
1-3-4-3: RAM problem.
1-4-1-1: RAM problem.
1-3-1-3: motherboard problem (keyboard controllerchip), keyboard or processor problem.
1-2-2-3: BIOS ROM checksum error - System ROM BIOS problem, re-seat or replace chip, try re-flashing BIOS or swap motherboard.
2-1-2-3: ROM copyright notice error - System ROM BIOS problem, re-seat or replace chip, try re-flashing BIOS or swap motherboard.
2-2-3-1: Test for unexpected interrupts - possible motherboard or processor problem.
1-2: ROM checksum error.
Award BIOS
1 long and 2 short beeps: Video adapter error
Repeated beeps: Memory error
Repeating high-low beeps: CPU problem.
High frequency beeps while running: Overheated CPU.