HP Compaq 6005 Pro Maintenance And Service Manual page 111

Power LED flashes Red four times, once every second, followed by a two second pause, and the computer beeps
four times. (Beeps stop after fifth iteration but LEDs continue flashing.)
Cause
Power failure (power supply is overloaded).
The incorrect external power supply adapter is being used.
Solution
1. Check if a device is causing the problem by removing
ALL attached devices (such as hard or optical drives).
Power on the system. If the system enters the POST,
then power off and replace one device at a time and
repeat this procedure until failure occurs. Replace the
device that is causing the failure. Continue adding
devices one at a time to ensure all devices are
functioning properly.
2. Replace the power supply.
3. Replace the system board.
The USDT power supply adapter must be at 135W and use
the Smart ID technology before the system will power up.
Replace the power supply adapter with the HP-supplied
USDT power supply adapter.
Solving Power Problems
101