HP dc7900 - Convertible Minitower PC Service & Reference Manual page 246

Table C-2 Diagnostic Front Panel LEDs and Audible Codes (continued)
Activity
Red Power LED flashes four
times, once every second,
followed by a two second
pause. Beeps stop after fifth
iteration but LEDs continue
until problem is solved.
Red Power LED flashes five
times, once every second,
followed by a two second
pause. Beeps stop after fifth
iteration but LEDs continue
until problem is solved.
Red Power LED flashes six
times, once every second,
followed by a two second
pause. Beeps stop after fifth
iteration but LEDs continue
until problem is solved.
Red Power LED flashes seven
times, once every second,
followed by a two second
pause. Beeps stop after fifth
iteration but LEDs continue
until problem is solved.
234 Appendix C POST Error Messages
Beeps Possible Cause
4 Power failure (power
supply is overloaded).
OR
The incorrect external
power supply adapter is
being used on the USDT.
5 Pre-video memory error.
6 Pre-video graphics error.
7 System board failure
(ROM detected failure
prior to video).
Recommended Action
1. Open the hood and ensure the 4 or 6-wire
power supply cable is seated into the
connector on the system board.
2. Check if a device is causing the problem by
removing ALL attached devices (such as
hard, diskette, or optical drives, and
expansion cards). 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.
3. Replace the power supply.
4. Replace the system board.
OR
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.
CAUTION: To avoid damage to the DIMMs or
the system board, you must unplug the computer
power cord before attempting to reseat, install, or
remove a DIMM module.
1. Reseat DIMMs.
2. Replace DIMMs one at a time to isolate the
faulty module.
3. Replace third-party memory with HP
memory.
4. Replace the system board.
For systems with a graphics card:
1. Reseat the graphics card.
2. Replace the graphics card.
3. Replace the system board.
For systems with integrated graphics, replace the
system board.
Replace the system board.