My HP DC7600 does not start.
Normall when I turn on the power supply switch, it would wait for me to press the power button. But now, as soon as I switch on power on the main supply, the power LED stars to blink in green continually (about each second, 1Hz cycle) and it never stops. Devices that connected to the PC and that have some LEDS also blink like wise. THERE ARE NO BEEPS.
I have read the manuals and troubleshooting guides from HP such as this one
http://h20000.www2.hp.com/bc/docs/support/SupportManual/c00368814/c00368814.pdf
but in vain. They all discribe failure cases in which the power LED blinks in red to give a hint on the problem. And these blinks are not continuous; they will come in packs of 2 to 10 in a cycle, cycles separated by a 2 second pause.
The only case described in the manuals of green power led being on are
1. Continuously on ==> Normal operation
2. Blinks in at 0.5Hz (once in 2 seconds) ==> in susended mode
I couldnt see the case in which the green power LED blinks continuously at 1Hz.
I tried a few tricks.
If I unplug CPU power cable from the main board, it behaves correctly; power LED blinks in red with the appropriate cylces to indicate that power supply is the problem.
I unseat the CPU, it again blinks the correct code in red, and beeps accordingly, to indicate that the CPU has been unseated. So it might not be a CPU problem.
I tried to unplug all devices, including RAM modules and hard drives, but in vain. GREEN LED blink continuously about once a second.
I have tried to reset CMOS; no change at all.
Does anyone have an idea of what the problem might be or what I should do?
Should I consider the mother board dead?