Solving Power Problems; Power Supply Shuts Down Intermittently; Computer Turned Off Automatically, Power Light Blinks Red Two Times Followed By A Two-Second Pause, And The Computer Beeps Two Times (Beeps Stop After Fifth Iteration But Lights Continue Blinking); Power Light Blinks Red Four Times Followed By A Two-Second Pause And The Computer Beeps Four Times (Beeps Stop After Fifth Iteration But Lights Continue Blinking) - HP ProDesk 400 G7 SFF Maintenance And Service Manual

Solving power problems

These tables provide common causes and solutions for power problems.

Power supply shuts down intermittently

Use this information to troubleshoot the computer.
Cause
If the computer has a voltage selector, voltage selector switch on
rear of computer chassis (some models) not switched to correct line
voltage (115 V or 230 V).
Power supply will not turn on because of internal power supply
fault.
Computer turned off automatically, power light blinks red two times followed by a two-
second pause, and the computer beeps two times (Beeps stop after fifth iteration but
lights continue blinking)
Use this information to troubleshoot the computer.
Cause
Processor thermal protection activated. A fan might be blocked or
not turning, or the heat sink is not properly attached to the
processor.
Power light blinks red four times followed by a two-second pause and the computer
beeps four times (Beeps stop after fifth iteration but lights continue blinking)
Use this information to troubleshoot the computer.
Cause
Power failure (power supply is overloaded).
ENWW
Solution
Select the proper AC voltage using the selector switch.
Replace the power supply.
Solution
1. Be sure 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, be sure that the fan cable is plugged onto the system
board header.
3. If the fan is plugged in and not spinning, replace it.
Solution
1. If the computer has a voltage selector, check that the voltage
selector, located on the rear of the power supply (some
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