HP Pavilion 8565C

Have you tried another monitor on the pc to see if the monitor works? Is there a green or amber light on the monitor? If you know you have a working monitor then thats not a good sign. Usually points to a bad processor or motherboard. Also make sure your monitor cable is tightened securly to the computer. Hope this helps.
Pete

By never finishes, how far do you think it gets?

Do the drives perform their self tests?

If no, you have a power supply problem.
Either a bad supply, or too high a load from a damaged component.

Do the keyboard lights flash?

If so, it likely does make it through POST.

Has there been a lightning storm in your area recently?

If so, inspect the modem or area of the on-board modem thoroughly.
If you see any signs of burnt or bulged parts, the modem is fried, and may have taken the PCI buss with it.

Have you tried re-setting the CMOS?
If all else looks okay, it is possible that the user or a virus corrupted the CMOS, or BIOS.

Next, check the parts in a known good PC:
CPU, RAM, drives, plug-in cards.

If all check good, then all thats left is the motherboard.

Chas

Strip the machine back to just a motherboard, 1 RAM module, and the video card.

If it does not boot and POST, then the problem is with the system board or CPU.

As I stated in my first answer, try the CPU, RAM and video in another PC.
If they all work individually, then the problem is the motherboard itself.

If you have a voltmeter, monitor the 5 volts on a drive connector while attempting to start the PC.

If the 5 volts goes away quickly, I would strongly suspect the motherboard.
Either the power supply switching circuit, an open circuit, or a short on the motherboard causing excess current draw.

Chas

Change memory lately ???

I've had Dells do this when it didn't like some new stick(s) of memory.

:-)

OK more questions. What happens when it quits? Does it lose all power? Does it sit there with a flashing cursor only? How are you sure it never finishes POST? Are you able to go to bios setup without it dying and you can change stuff there? This onesounds temptingly easy but need more info. It seems that if you observe this start up routine, carefully, it could lead to the answer. It sounds almost as if you have a MASTER BOOT RECORD problem, but if you are sure it never finishes post then... not.

swap mobo, keep add in cards and memory!

Play taps your processor and/or motherboard has died. I would venture to say replace processor first. If it doesn't work replace motherboard.
Since both are expense, I would buy a new computer.

When you say you are "working on" what exactly do you mean? Was the computer ever working, or is that the reason you are working on it?

Personally, I wouldn't go out and buy a new processor and motherboards just yet!

If you let me know what processor is in it I can give you some details of how to test it with a multi-meter.

I think answer 3 is your best bet. Take out all of the pci cards (minus video), unplug all connectors on the back, keyboard and mouse included, unplug the IDE cables, and unplug the power cord from the motherboard. Push the power button a few times.This will drain the motherboard of any power it is still holding (this only works if it is an ATX motherboard). Plug the cord back in and turn the machine on. If your still getting nothing, your beyond me. :)

Good Luck Bro

I had a problem with another Pavilion that would start, run for 3-4 seconds then shut down. It turned out that the power switch on the front panel was sticky and did not slide back out when I took my finger off the button. A shot of silicon lubricant on the switch shaft cured the problem. This is not the oval shaped front panel button - it is the one screwed to the chassis behind the plastic front panel. It is a pain to remove the front panel to get to the button so you may want to confirm this first by pulling off the side panel, removing the black & red wire pair from its motherboard pins and momentarily shorting the pins . If it starts and keeps running, the problem is the switch.