Solving Power Problems - HP EliteDesk 705 G1 Microtower Maintenance And Service Manual

System does not power on and the LEDs on the front of the computer are not flashing.
Cause

Solving power problems

Common causes and solutions for power problems are listed in the following table.
Power supply shuts down intermittently.
Cause
If equipped with a voltage selector, voltage selector switch
on rear of computer chassis (some models) not switched to
correct line voltage (115V or 230V).
Power supply will not turn on because of internal power
supply fault.
Computer powered off automatically and the Power LED flashes Red two times, once every second, followed by a two
second pause, and the computer beeps two times. (Beeps stop after fifth iteration but LEDs continue flashing.)
Cause
Processor thermal protection activated:
A fan may be blocked or not turning.
OR
The heat sink is not properly attached to the processor.
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).
130 Chapter 8 Troubleshooting without diagnostics
Solution
4. Check to see if the 5V_aux light on the system board is
turned on. If it is turned on, then replace the power
button assembly.
5. If the 5V_aux light on the system board is off, then
replace the power supply.
6. Replace the system board.
Solution
Select the proper AC voltage using the selector switch.
Replace the power supply.
Solution
1. Ensure that the computer air vents are not blocked and
the processor cooling fan is running.
2. Open the access panel, press the power button, and
see if the processor fan (or other system fan) spins. If
the fan does not spin, make sure the fan cable is
plugged onto the system board header.
3. If fan a plugged in and not spinning, replace it.
Solution
1. If equipped with a voltage selector, check that the
voltage selector, located on the rear of the power supply
(some models), is set to the appropriate voltage. Proper
voltage setting depends on your region.
2. Open the access panel and ensure the power supply
cable is seated into the connector on the system board.
3. Check if a device is causing the problem by removing
ALL attached devices (such as hard drives or optical
drives and expansion cards). Power on the system. If